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PubMed1977

Leptofibrils in intrafusal muscle fibres of muscle spindles in the domestic fowl.

Leptofibrils consisting of narrow dark and wide light bands at regular periods are commonly found in intrafusal muscle fibres of chicken muscle spindles. They are particularly abundant in intrafusal muscle fibres with the loose type of myofilaments. They occur either at the periphery of intrafusal muscle fibres or in deeper regions, or even close to sensory nerve terminals. Dark bands of some peripheral leptofibrils vary considerably in size and appear less regular in configuration. Lateral extensions from the dark bands may occur with or without interconnections. Lateral attachments to myofilaments at the immediate neighbourhood may also occur.

Animals↗
PubMed1980

Phagocytosis of spermatozoa by the ovum of the domestic fowl, Gallus gallus at the time of fertilization.

Spermatozoa with intact acrosomes, as well as those coming into contact with the ovum at a smaller angle, and morphologically abnormal spermatozoa reach the plasma membrane of the ovum via an extensively dissolved zone of the inner layer of the vitelline membrane. This zone is assumed to be formed by overlapping of two or more tunnels formed by spermatozoa that had previously come into contact with the ovum. When a spermtozoon comes into contact with the plasma membrane of the ovum, many cytoplasmic processes extend outwards and cover it. Thereafter, the plasma membranes of the processes fuse, thereby phagocytizing the spermatozoon. It is assumed that the he phagocytized spermatozoa cannot undergo transformation into male pronuclei and that they degenerate soon after phagocytosis.

Animals↗
PubMed1980

Scanning and transmission electron microscopic observations of the cloacal epithelia of the domestic fowl.

The epithela of the three divisions (coprodaeum, urodaeum, proctodaeum) of the cloaca of the hen, and of the excretory ducts (colon, ureter, vagina) which join the divisions, are described using light microscopy, and scanning and transmission electron microscopy. Each region of the cloaca has its typical epithelium. Special attention is focussed in this study on the boundaries between the different epithelia. The coprodaeal epithelium does not differ considerably from that of the colon; a transitional zone is not visible. Distinct border zones, however, are observed between the other regions (ureter--urodaeum; vagina--urodaeum and proctodaeum; urodaeum--proctodaeum; proctodaeum--cutis). Although the vaginal opening is generally thought to lie in the urodaeum, our investigations show that at the vaginal opening into the cloaca the ciliated epithelium changes, on one border to a secretory epithelium characteristic of the urodaeum and on the other border to that characteristic of the proctodaeum. These observations are discussed in relation to functional aspects.

Animals↗
PubMed1981

Fate of spermatozoa that do not participate in fertilization in the domestic fowl.

The fate of spermatozoa that do not participate in fertilization was investigated by electron microscopy. After artificial insemination, we observed several spermatozoa between the fibers of the outer layer of the vitelline membrane of the ovum. One or more spermatozoa were also found in a phagocytic vesicle of macrophages located in the intercellular space of the mucosal epithelium of the infundibulum or in the outer layer of the vitelline membrane. From these observations, we assume that the superfluous spermatozoa in the lumen of the anterior part of the oviduct might be removed by inclusion into the outer layer of the vitelline membrane and by phagocytosis by macrophages.

Animals↗
PubMed1980

Immunocytochemical demonstration of met-enkephalin in the central nervous system of the domestic fowl.

In the central nervous system of the male domestic flow, metenkephalin (ENK) immunoreactive perikarya and fiber tracts as well as extensive but sharply delimited fiber networks were visualized by means of the PAP technique. The most striking results were: (1) The demonstration of an association of ENK-containing structures with branchial nerves; (2) the spatial relationship of ENK-containing perikarya and fibers to somatostatin (SOM) and arginine-vasotocin (AVT)-immunoreactive systems; (3) the presence of dense and extensive ENK fiber networks within (a) the caudo-basal wall of the third ventricle and (b) the septal-preoptic area; in both regions mainly ENK fibers, but also SOM and AVT fibers, may cross to the contralateral side.

Animals↗
PubMed1987

Nucleotide sequences and unusual electrophoretic behavior of the W chromosome-specific repeating DNA units of the domestic fowl, Gallus gallus domesticus.

Nucleotide sequences of three independently cloned repeating units of the W chromosome-specific repetitive DNA sequences ("XhoI family") of the chicken were determined. All three units are 717 bp long with XhoI sites at both ends. There are only 21 sites out of 717 bases where a single base change occurs in one of the three clones. Each of these repeating units consists of 34 tandem repeats of about 21 bp. Sequences of some members of these internal repeats are not well conserved, but the majority of the repeats are characterized by the presence of (A)3-5 and (T)3-5 clusters separated by 6-7 relatively G + C-rich base pairs. One striking feature of the cloned 717 bp repeating units is that they migrate unusually slowly on electrophoresis in polyacrylamide gels. The same feature is also shown by a genomic population of the 0.7 kb repeating units recovered from XhoI digests of the genomic DNA of the female chicken. This anomalous behavior is attributed to the occurrence of DNA curvatures because of the above sequence characteristics and partial recovery of the electrophoretic mobility in the presence of distamycin A. Another feature of the 717 bp repeating unit is the presence of 438 and 159 nucleotide-long open reading frames (ORFs) at each end of the unit. A possible function of the XhoI family sequences in the heterochromatization of the W chromosome and the significance of the ORFs are discussed.

Animals↗