Biomedical subjects

C J Wensing

Publications and source records attributed to C J Wensing.

At least 55 records · Page 3Linked to original sources

PubMed1984

Sertoli cell development of pig testis in the fetal and neonatal period.

The Sertoli cells of pig fetuses from 35 days postcoitum until 1 mo after birth have been investigated by light and electron microscopy in decapitated animals and their control littermates, as well as in untreated animals. Until 52 days postcoitum, Sertoli cells change in form during the formation of sex cords but from then onwards they are rather uniform. They primarily display an elongated nonindented nucleus with one or more prominent nucleoli, a well-developed Golgi apparatus, and in the basal compartment below or beside the nucleus, a large lipid droplet. There are large quantities of rough endoplasmic reticulum (RER) from 52 days postcoitum onwards, often with complex whirl forms and a parallel arrangement of profiles with relatively few ribosomes. After birth their numbers seem to be somewhat less, and by 1 mo after birth the RER profiles are often shorter and almost free of ribosomes. Clustered ribosomes are found in large quantities throughout the period under investigation. Especially in the early fetal period, the endoplasmic reticulum (ER) profiles show prominently filled cisternae. Mitochondria are mostly long and slender, or small and ovoid. Most have lamellar cristae, but mixed lamellar-tubular cristae can also be seen. Between decapitated, control and untreated animals no obvious ultrastructural differences could be observed. The peritubular cell sheath surrounding the sex cords did not show signs of differentiation into a layer of myoid cells.

Animals↗

PubMed1984

Effect of experimental microvascular orchidopexy on spermatogenic cell differentiation in the testes of the dog.

Experimental microsurgical orchidopexy was undertaken in 15 healthy mongrel dogs by anastomosing the testicular artery and vein to the ipsilateral caudal epigastric vessels. At pre-selected post-operative intervals of 4 weeks, 5 or 8 months the results were morphologically and histologically evaluated by the 'testicular biopsy score count' method. This method is based on the presence of the main spermatogenic types arranged in order of maturity. Between the mean scores of the normal and the operated testes there was a significant difference. The differentiation of the spermatogenic epithelium of the reconnected testis is slightly hampered, but not seriously.

Animals↗

PubMed1984

Effects of adrenergic agonists and antagonists on the blood pressure and heart rate of the pig fetus.

The effects of adrenergic agonists and antagonists on blood pressure and heart rate were investigated in 18 chronically catheterised pig fetuses aged between 102 and 109 days of gestation (term is 114 days). One fetus had been decapitated in utero at 42 days of gestation. The alpha adrenergic agonist methoxamine produced a small but dose dependent hypertension and a dose related slowing in heart rate. The beta adrenergic agonist isoprenaline decreased mean arterial pressure in a dose related manner and produced tachycardia. Propranolol, a beta adrenergic blocker, increased mean arterial pressure and decreased heart rate. The response to subsequent alpha adrenergic blockade with phentolamine was hypotension and a slight bradycardia. Decapitation at 42 days of gestation did not seem to change the fetal responsiveness to adrenergic agonists but removed the blood pressure response to beta blockade. These observations indicate that the heart and circulation of the pig fetus are under adrenergic vasomotor control during late gestation.

Adrenergic Agonists↗

PubMed1984

Cytoplasmic filaments in fetal and neonatal pig testis.

Leydig cells in developing fetal pig testis contained during the fetal regressive phase large accumulations of intermediate filaments. Before and after this period these filaments were arranged in a criss-cross fashion. In the pig as well as in the dog testis these filaments have been characterized as vimentin. Within the vimentin aggregates occasionally a weak positive actin reaction was seen in pig but not in dog Leydig cells. Microfilaments were hardly observed. Most Sertoli cells contained a layer of actin microfilaments close to the basal cell membrane. In the lower cell compartment and around the nucleus (intermediate) vimentin filaments could be observed in a criss-cross configuration.

Aging↗

PubMed1983

Nerve endings in the pulmonary trunk, ductus arteriosus and aorta of intact and decapitated pig fetuses.

Nerve fibres reactive to acetyl-thiocholine, and tissues showing catecholamine fluorescence were examined in the pulmonary trunk, ductus arteriosus and aorta of 28 pig fetuses between 31 and 113 days of gestation (term = 114 +/- 1 days). Eight additional fetuses, which had been decapitated in utero at 40-43 days, were also studied at ages between 51 and 114 days of gestation. Spherical micro-networks of nervous tissue reactive to acetyl-thiocholine are present in the adventitia on the cranial aspect of the pulmonary trunk and ductus arteriosus, between the aorta and pulmonary trunk, and on the caudal aspects of the pulmonary trunk and the pulmonary arteries. These fibres invest spherical clusters of catecholamine containing cells which are well supplied with blood vessels. Nerve fibres which fluoresce are also found in association with these cells. Decapitation in utero does not appear to affect the distribution of morphology of these structures. The observations show that structures are present in the major arteries of the fetal pig which may act as sensory receptors, and that these structures are unaffected by chronic vagotomy of the fetus produced by decapitation early in gestation.

Animals↗

PubMed1983

Development of nervous tissue in the heart of the fetal and neonatal pig and the effect of decapitation in utero.

The development and distribution of the nerves in the heart of the pig was studied macroscopically and by light microscopy. Hearts were collected from 86 fetuses between 31 and 114 days of gestation (term = 114 days), from 12 neonatal pigs aged 9 and 20 days and from 6 adult sows of the Dutch Landrace breed. The effect of vagotomy produced by decapitation in utero at 40-43 days was studied in an additional 24 hearts from fetuses aged between 51 and 114 days of gestation. The amount of acetyl-thiocholine reactive fibres increases in the atria, A-V node and ventricles throughout gestation. At every age the amount of nervous tissue is highest in the A-V node and lowest in the ventricles. Hearts from decapitated fetuses have smaller amounts of nerve tissue than those from intact fetuses at every age studied. Ganglia are present in both intact and decapitated fetuses. Fluorescent cells containing catecholamines are observed in hearts from fetuses as young as 35 days gestation. Although fluorescent nerve fibres are rarely seen in hearts at 70 days gestation, more fibres are present near birth and thereafter there appears to be a considerable increase in the number of fibres and in the intensity with which they fluoresce. These results show that there is substantial nerve growth into the heart of the pig during gestation and that catecholamine containing nerve fibres develop later than those reactive to acetyl-thiocholine.

Animals↗

PubMed1983

The effects of gestational age and chronic fetal decapitation on arterial blood pressure in the pig fetus.

Blood pressure was measured in anaesthetized pig fetuses decapitated at 40-43 days of gestation and in intact fetuses between 35 and 112 days of gestation (term is 114 days). In the intact fetuses arterial blood pressure increased significantly from 0.8 +/- 0.1 kPa (mean +/- SEM) at 35 days to 5.8 +/- 0.2 kPa at 112 days (P less than 0.05). The arterial blood pressure of decapitated fetuses was similar to that of intact fetuses at 70 days of gestation (2.7 +/- 0.4 kPa vs. 2.5 +/- 0.1 kPa, respectively) but did not change with increasing gestational age thereafter. Hence in late gestation (greater than 90-100 days) the arterial blood pressure of the decapitated fetuses was significantly less than that of intact fetuses (P less than 0.05). These observations demonstrate that the control of blood pressure in the pig varies with gestational age and suggest that the developmental changes occurring after about 100 days gestation require tissues within the head.

Animals↗

PubMed1983

The effect of transection of the main vascular and nervous supply of the testis on the development of spermatogenic epithelium in the pig.

The treatment of cryptorchidism in boys by the orchiopexy procedure is variably successful due to several technical problems. In order to study some of these problems a series of experiments in the male pig were undertaken. Experimental simulations of the orchiopexy procedure in the inguinal canal in male pigs with normally descended testes gave rise to damage of the spermatogenic epithelium. Cooling experiments of abdominal testes in adult, naturally cryptorchid pigs indicate that the arrest of spermatogenesis in abdominal testes is not due to an inborn defect but is caused by maintenance of the testes at the abdominal temperature. Evaluation of the data of the interventions with the testicular artery, vein, and nerve, either separately or in combination in the abdomen, showed that there was no effect on the spermatogenic epithelium in any one of the five experimental groups. These experiments confirm that in cryptorchid boys transection of the testicular artery and vein in the abdomen may be indicated if a tension-free fixation of the testis in the scrotum is not achievable, provided that alternate routes are able to take over the main blood supply to the testis.

Animals↗

PubMed1983

Ovarian development in control and decapitated pig fetuses.

Ovarian development was studied in control and decapitated pig fetuses. Fetuses were decapitated at 42 days postcoitum. At 51, 61, 74, 90 and 112 days postcoitum decapitated and control females were collected. Ovarian weight gradually increased during development in control animals. Deprivation of pituitary hormones as a result of fetal decapitation did not cause a decline in ovarian weight increase. Germ cell maturation in control and decapitated fetuses proceeded in a similar fashion, with secondary follicles being the most advanced stage. Enzyme histochemical activity was present in the primary interstitial gland cells and in granulosa cells and was similar in normal and decapitated fetuses. Both NADH diaphorase activity and 3 beta-hydroxysteroid dehydrogenase activity increased from 51 to 74 days and remained relatively constant thereafter. Since fetal decapitation in the pig hardly influences ovarian development, pituitary dependency of the fetal ovary in the pig is unlikely.

3-Hydroxysteroid Dehydrogenases↗

PubMed1983

The effect of norepinephrine, isoprenaline and acetylcholine on the testicular and epididymal circulation in the pig.

Blood flow to the testis and epididymis of 7 anaesthetized male pigs was measured using electromagnetic blood flow sensors. An average blood flow to the testis of 12 ml/min/100 g and in the epididymal arteries of 19 ml/min/100 g was measured. The effect of intravenously administered norepinephrine, isoprenaline and acetylcholine on alpha and beta 2 adrenergic and cholinergic receptor sites, respectively, was investigated. As neither norepinephrine nor isoprenaline, nor acetylcholine changed vascular conductance of the testis, we could not demonstrate adrenergic and cholinergic receptor activity. The possibility of autonomic regulation by the nonvascular smooth muscles of the spermatic cord and the inner layer of the tunica albuginea has been discussed.

Acetylcholine↗

PubMed1983

Compensatory development of a patent vascular supply to the testis after intra-abdominal transection of its main blood vessels.

The compensatory development of testicular vascular supply was studied in the pig after intra-abdominal transection of the testicular artery and vein at a young age (2 months). Post-pubertally (6 1/2 months) in these animals, normal spermatogenic epithelium and testosterone values were found. Functionally important anastomoses developed from latent connections between the vasal and testicular arteries at the coiled part of the latter and on the surface of the testis. Blood supply to the testes of operated animals reached 80% of values measured in control animals.

Animals↗

PubMed1983

The role of a non-androgenic testicular factor in the process of testicular descent in the dog.

Previous experiments with orchidectomized foetal and neonatal dogs have shown that the testis can induce outgrowth as well as regression of the gubernaculum testis and consequently, govern both the first and second phases of testicular descent. The aim of this study was to test whether it was possible to prevent the effects of orchidectomy on the gubernacular reaction and on epididymal migration by the administration of testosterone or by auto-transplantation of testicular tissue. In dogs, orchidectomized during foetal life and supplemented with testosterone, gubernacular regression was not completely prevented, and some descent of the remaining epididymis was obvious. However, the descent was less than in normal, intact animals. In dogs orchidectomized neonatally and supplemented with testosterone, the gubernacula showed normal regression and an almost normal descent of the epididymis. In dogs orchidectomized neonatally and supplemented with an auto-transplant of testicular tissue into to the scrotum, normal gubernacular development and normal epididymal descent were observed. We concluded that together with an unidentified non-androgenic testicular factor, testosterone from the testis appears to play a role in the outgrowth phase of the gubernaculum and consequently, in the first phase of testicular descent. In addition, testosterone was found to induce gubernacular regression in the second phase of testicular descent.

Animals↗

PubMed1983

Morphological development of the thyroid gland and serum T4-concentration in the intact and decapitated pig fetus.

The morphological and functional development of the fetal pig thyroid gland between 50 and 110 days post coitum have been examined in the normal pig fetus and after fetal decapitation at 42 days postcoitum. Body length and body weight developed at the same rate, comparing control and decapitated animals. Thyroid gland weight increased between 50 days and 110 days from 1.3 +/- 0.5 mg (SD) to 130.0 +/- 35.0 mg in control fetuses and from 0.9 +/- 0.2 mg to 113.4 +/- 23.0 mg in decapitated fetuses. A number of histomorphometrical parameters in thyroid tissue were measured. No significant differences in follicular epithelial height were observed between decapitated and control animals at 75 and 110 days. In control animals follicles increased both in size and number. In decapitated animals the follicles increased strikingly in number, but only slightly in size. Although colloid was formed in glands of decapitated animals, it was much less than in control fetuses. The gland of decapitated animals of 110 days resembled histologically the gland of much younger control animals (60 to 75 days). Gland development after fetal decapitation at 42 days may represent autonomous development when Thyroid Stimulating Hormone (TSH) is depleted. Serum thyroxine concentration (T4) was determined by radioimmunoassay and increased in control animals from 0.06 +/- 0.01 micrograms/100 ml to 4.18 +/- 0.87 micrograms/100 ml at 110 days, the greatest rate of increase being observed between 64 and 90 days. In decapitated fetuses serum T4 remained very low, namely less than 0.20 micrograms/100 ml. It is very unlikely that any significant transfer of T4 from mother to fetus or from one fetus to another occurred. Both the rise in serum T4 and the enlargement of the follicles may be TSH dependent events in fetal pig thyroid gland development, whereby the sudden rise is serum T4 precedes the greatest rate of increase in follicle size.

Animals↗

PubMed1982

Leydig cell development of pig testis in the early fetal period: an ultrastructural study.

Leydig cell development in the pig testis occurs in three periods (an early fetal, the perinatal period, and the period from puberty onward). The earliest of these periods was investigated ultrastructurally. The early fetal period starts immediately after gonadal differentiation, approximately 27 days postcoitum (p.c.), and finishes at about 60 days postcoitum. Dates of observation were 35, 52, and 62 days p.c. At 42 days p.c. some animals were decapitated. Leydig cells at 35 days p.c. are characterized by an oval nucleus, vesicular or branched tubular smooth endoplasmic reticulum (SER), and a small quantity of rough endoplasmic reticulum (RER). The RER has two forms: a short and a long profile. The latter is closely coupled with mitochondria. The mitochondria mostly have tubular cristae. From 52 days p.c. onward the degree of coupling lessens, and it vanishes at 62 days p.c. At 52 and 62 days p.c. a very large amount of 10 nm filaments and a slight decrease in SER can be observed. The SER now has a branched tubular form, and the presence of polygonal dense bodies is also characteristic. Decapitation does not disturb normal development of the Leydig cells in the observation period. No obvious differences from controls can be observed.

Animals↗

PubMed1982

The prevention of orchiopexy-induced testicular lesions in the pig.

From previous experiments it was concluded that failure of spermatogenic cells to differentiate after orchiopexy seems to be due to surgical trauma. Furthermore it appeared that in normally descended testes of naturally unilaterally cryptorchid pigs subjected to orchiopexy, the spermatogenic epithelium was poorly developed as compared with that of scrotal testes of unilaterally cryptorchid pigs that had not undergone the surgical procedure. Even simple inguinal surgery in unilaterally naturally cryptorchid piglets may already give rise to severe histological lesions in the spermatogenic epithelium of the normally descended contralateral testes at adulthood. On the other hand extirpation of the retained testis by laparotomy does not affect the spermatogenic epithelium in the contralateral scrotal testis. From these experiments it may be concluded that with regard to the prevention of sterility in unilaterally cryptorchid pigs it may be preferable to extirpate the retained testis rather than to perform an orchiopexy.

Animals↗

PubMed1982

Changes in serum FSH concentrations in the pig during development.

Serum FSH concentrations were measured in fetal and prepubertal pigs between 40 days postcoitum and 25 weeks after birth. In addition, serum FSH was estimated in prepubertal, unilaterally cryptorchid, freemartin and castrated pigs. The average serum FSH concentrations in male and female fetuses was low (less than 2 ng/ml) until 80 days p.c. During the remaining fetal period, concentrations in females were elevated (7.9 +/- 0.4 ng/ml) and remained fairly constant after birth (16.3 +/- 0.8 ng/ml). In the male, serum FSH concentrations gradually rose to 22.5 +/- 5.5 ng/ml during the first 3 weeks after birth and declined thereafter. The changes in FSH concentrations in male pigs are reflected in gonadal-development. In contrast, in fetal and prepubertal females, ovarian development seems not to be influenced by changes in serum FSH concentrations. Unilateral cryptorchidism did not affect serum FSH concentrations. After castration, however, concentrations rose significantly. In freemartin pigs concentrations were similar to those in female pigs.

Animals↗

PubMed1982

The effect of orchidectomy on gubernacular outgrowth and regression in the dog.

To test whether the outgrowth and regression of the gubernaculum testis and consequently testicular descent are testis dependent, unilateral and bilateral orchidectomies were performed on foetal dogs at 49 days post coitum (p.c.), and on newborns at day 0 and day 3 after birth. Prior to these experiments the vascularisation of the testis, epididymis and gubernaculum had been studied to develop a method of orchidectomy, in which the vascularisation of the gubernaculum and epididymis was minimally damaged. After bilateral orchidectomy at 49 days p.c., outgrowth of the gubernaculum stopped completely, and the epididymis remained in its original abdominal position. After bilateral orchidectomy at birth, the descent of the remaining epididymis from an intra-abdominal to an extra-abdominal position was retarded, due to retarded regression of the gubernaculum. Bilateral orchidectomy 3 days after birth resulted in a slightly retarded gubernacular regression. After unilateral orchidectomies the effects were similar but less pronounced. It was concluded that the testis induces and maintains the outgrowth and initiates regression of the gubernaculum, thereby regulating the process of testicular descent. However, once the regression had started, it appeared to proceed more or less autonomously.

Animals↗

PubMed1981

The influence of elevated testicular temperature and scrotal surgery on the number of gonocytes in the newborn pig.

Morphological changes become apparent shortly after birth in the abdominally located testes of the pig. To test the influence of temperature on gonocyte multiplication, scrotal testes of newborn piglets were subjected to continuous artificial heating. It was found that in the young pig during the first 2 weeks of life when the mitotic activity of the gonocytes is high, they are very sensitive to a combination of elevated testicular temperature and scrotal surgery.

Animals↗