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PubMed1976

Ultrastructural observations on the differentiation of spermatids in man.

Ultrastructural aspects of the normal development of human spermatids are presented. Eight typical pictures of differentiation of spermatids are described based on cytological details of the acrosome, nucleus and tail. The transient appearance of a spindle-shaped body, connected to the principal piece of the tail, is pointed out. In most cases, malformed spermatids have developmental disturbances of only one component of the cell, e.g. of the acrosome, nucleus or tail. Some typical malformations are described.

Acrosome↗
PubMed1975

Mutagenic effect of thioTEPA in laboratory mice. V. Influence of female genotype on realization of dominant lethal mutations induced in the spermatids of males.

Hybrid male mice (F1 males derived from the cross DBA/2 x AKR) were injected intraperitoneally with thio-TEPA at a 2 mg/kg dose. The mutagenic effect was determined from the frequency of dominant lethal mutations induced in spermatids of males. The males were mated during the second and the third week after the injection to females of the strains C57BL/6, CBA/lac and to the F1 hybrid females derived from the cross CBA x C57BL/6 differing in the frequency of spontaneous and induced aberrations in bone marrow cells. In the course of investigation of pregnant C57BL/6 females F1 (CBA x C57BL/6) and CBA/Lac females the frequency of dominant lethals induced in late spermatids was established to be 63.4, 54.0 and 37.9% respectively. The differences were interpreted as the evidence of different rates of recovery of a certain proportion of premutational lesions of the chromosomes of pserms in fertilized egg cells of female mice. No significant differences between the groups of females were observed in case of the treatment of early spermatids. It is establihsed that the F1 hybrids derived from the cross DBA/2 x AKR are characterized by a high mutability.

Animals↗
PubMed2025

Development and validation of a deep learning model based on cascade mask regional convolutional neural network to noninvasively and accurately identify human round spermatids.

INTRODUCTION: The difficulty of identifying human round spermatids (hRSs) has impeded applications of the human round spermatid injection (ROSI) technique. RSs can be accurately screened through flow cytometric analysis utilizing the Hoechst fluorescence profile reflecting DNA, but this method is not suitable for isolating hRSs due to the toxicity associated with Hoechst staining. OBJECTIVE: To evaluate the capacity of a deep learning model grounded in a cascade mask region-based convolutional neural network (R-CNN) for the noninvasive and accurate identification of hRSs. METHODS: In this study, we presented the development and validation of a deep learning model for identifying hRSs through the analysis of 3457 optical light microscope images of sorted hRSs obtained via flow cytometric analysis. The model's accuracy and specificity were evaluated by calculating the mean average precision (mAP). Furthermore, a double-blind experiment was conducted to access the reliability of the proposed model in accurately identifying hRSs. It detected the expression of protamine (PRM1) and/or peanut lectin (PNA), which are established markers for RSs. RESULTS: Our deep learning-based model demonstrated a high precision, achieving a mAP of over 0.80 for isolating hRSs in test datasets. The expression of PRM1 and/or PNA was observed in all cells noninvasively selected by our AI model during an independent double-blind test. This phenomenon confirmed the accuracy and effectiveness of the proposed model. The model's capability for noninvasive and accurate isolation of hRSs among spermatogenic cells highlighted its robustness and generalizability for clinical applications. CONCLUSION: The deep learning AI model based on a cascade R-CNN has the ability to accurately identify hRSs among spermatogenic cells. The application of this noninvasive method, which requires no additional procedures in clinical practice, is able to facilitate the widespread implementation of ROSI technique. Therefore, it can provide patients with spermatogenic arrest the opportunity to become biological fathers.

Humans↗
PubMed1976

Formation of packaging units in circket late spermatid nuclei as visualized by spreading techniques (1).

The nuclear organization of a particular step of cricket late spermiogenesis was examined by an electron microscope study of spermatids dispersed by air-liquid surface tension. Cell spreading techniques facilitate a display of condensing spermatid nuclei sufficient to allow interpretation of chromatin packaging processes. Results indicate that nuclei of late developing cricket spermatids are integrated by multiple packaging units as the result of an orderly aggregation of individual chromatin fibers. Each packaging unit consists of a thick fasicle, formed by the alignment of smooth chromatin fibers, which frays out into tassels of looped fibers.

Animals↗
PubMed1977

Sertoli-sertoli junctions and Sertoli-spermatid junctions after efferent ductule ligation and lanthanum treatment.

Seminiferous tubules, partially dilated by ligation of the efferent ductules, were examined after treatment with lanthanum. Lanthanum penetrated the intercellular spaces of the seminiferous epithelium, but only to the level of the Sertoli-Sertoli junctions. Further penetration from the interstitial surface of the tubule was restricted by membrane fusions (tight junctions) at the junctional complex. Lanthanum also penetrated the epithelium from the luminal surface permeating the adluminal intercellular spaces, including the site of the Sertoli-spermatid junction. The lanthanum occupying the Sertoli-spermatid junctional site appeared as a slightly narrower electron-opaque zone than that found in the non-specialized intercellular areas. The findings clearly reveal that only the Sertoli-Sertoli junctional site forms a restrictive barrier. In contrast to the specializations of plasma membrane which form the tight junction, the associated filaments and cisterna of endoplasmic reticulum may be components more directly related to maintaining and regulating cell adhesion.

Animals↗
PubMed1978

A further type of transient cytoplasmic organelle in human spermatids.

Osmiophilic granules with surrounding vesicles resembling flower-like structures occur transiently during the differentiation of human spermatids. These organelles are incorporated into the residual bodies when mature spermatids are released from the germinal epithelium.

Cytoplasmic Granules↗
PubMed1979

"Cytogenetic" studies of spermatids of mice carrying Cattanach's translocation by flow cytometry.

The DNA content of spermatids of mice carrying Cattanach's translocation has been measured with high precision by flow cytometry. The observation that the two peaks of DNA content in the haploid region of the DNA histograms represent X- and Y-bearing spermatids was tested and confirmed. Using flow cytometry, the difference in DNA content between the X and Y chromosomes in these mice was measured to be 5.2 +/- 0.1% of the total haploid genome as compared to 3.4 +/- 0.1% in normal mice. These results demonstrated the precision of flow cytometry for cytogenetic studies. Additional information on spermatogenesis in mice bearing Cattanach's translocation was obtained and showed a gradual loss of cells during spermatogenesis in those bearing the balanced form of the translocation.

Animals↗
PubMed1977

RNA synthesis in spermatocytes and spermatids and preservation of meiotic RNA during spermiogenesis in the mouse.

The rate of RNA synthesis at different stages of spermatogenesis in the mouse, and the preservation of RNA from the diploid to the haploid phase of spermatogenesis were studied in homogeneous germ cell fractions separated by velocity sedimentation at unit gravity. The uridine pool expansion method was used for determining the rate of RNA synthesis: seminiferous tubules were labelled in culture with increasing concentrations of [3H]-uridine and the incorporated radioactivity was estimated in cell fractions separated by velocity sedimentation. The results indicate that before nuclear elongation, round spermatids (steps 1 to 8 of spermiogenesis) synthesize RNA at the same rate per DNA content as middle-late pachytene spermatocytes. The preservation of RNA molecules synthesized in meiosis was investigated by labelling pachytene spermatocytes with T3H]uridine in vivo and collecting samples of germ cells at definite stages of spermatogenesis at various time intervals thereafter. The results show that a considerable proportion the RNA synthesized during the pachytene stage is preserved through spermatid development until late spermiogenesis.

Animals↗
PubMed1979

Ultrastructural characteristics of idiopathic spermatidic arrest.

Previous studies on some cases of idiopathic spermatidic arrest showed an anomaly in glucose metabolism, in particular decreased utilization of glycogen at stage 3 of spermatogenesis, when condensation of the spermatid head commences. Histological patterns seen on light microscopy confirmed the reduced utilization of glycogen at stage 3 of spermatogenesis. Electron microscopy revealed an arrest at stage 3 of spermiogenesis and, at the cytoplasm level of the Sertoli cell, a modification in the smooth endoplasmic reticulum characterized by the presence of dilated cisternae. From a morphological viewpoint, the equivalent of a biochemical modification which characterizes this maturation disorder in the germinal epithelium is hypothesized.

Humans↗
PubMed1977

Ultrastructural studies on the differentiation of spermatids in the domestic fowl.

Four phases of spermatid maturation are recognized on the basis of nuclear morphology. The formation of the acrosome, perforatorium and axial filament complex are described in relation to these phases. The functional significance of the microtubular systems in nuclear elongation and spermatid curvature are discussed. A membranous structure, hitherto unidentified, and referred to in this study as the 'membrane body' is compared with the chromatoid body. Morphological evidence suggests that this structure, together with the annulate lamellae, removes excessive nuclear material.

Animals↗
PubMed1975

[The mutagenic effect of thioTEPA in laboratory mice. V. The influence of female genotype on the realization of dominant lethal mutations induced in male spermatids].

Hybrid male mice (F1 males derived from the cross DBA/2 X AKR) were injected intraperitoneally with thio-TEPA at a 2 mg/kg dose. The mutagenic effect was determined from the frequency of dominant lethal mutations induced in spermatids of males. The malles were mated during the second and the third week after the injection to females of the strains C57BL/6, CBA/lac and to the F1 hybrid females derived from the cross CBA X C57BL/6 differing in the frequency of spontaneous and induced aberrations in bone marrow cells. In the course of investigation of pregnant C57BL/6 females, F1 (CBA X C57BL/6) and CBA/Lac females the frequency of dominant lethals induced in late spermatidis was established to be 63.4, 54.0and 37.9% respectively. The differences were interpreted as the evidence of different rates of recovery of a certain proportion of premutational lesions of the chromosomes of sperms in fertilized eggcells of female mice. No significant differences between the groups of females were observed in case of the treatment of early spermatids. It is established that the F1 hybrids derived from the cross DBA/2X XAKR are characterized by a high mutability.

Animals↗
PubMed1977

Stages of spermatids in the domestic fowl: a light microscope study using Araldite sections.

Ten stages in spermatid maturation have been identified in the testis of the domestic fowl, using Araldite-embedded material. Identification of stages 1-3 was dependent on the position of the idiosome and the proacrosome granule. Stages 4-8 were identified by the shape of the acrosome, shape and length of nucleus, and the shape of the cell, The presence of the manchette and the mitochondrial sheath helped identify stages 9 and 10. It is suggested that the identification of stages of spermatids in this manner may be of use in ascertaining whether or no a seminiferous epithelial cycle is present in this species.

Acrosome↗
PubMed1977

Cytoplasmic annulate lamellae and intranuclear membranes in human spermatids and sperm.

In human spermatide cytoplasmic annulate lamellae and intranuclear lamellae were found. In the cytoplasm, the annulate lamellae may vary from 3 to 11 layers of cisternal structures. There is evidence that the annulate lamellae are formed from the outer nuclear envelope. The intranuclear membranes are often seen directly connected to the inner nuclear membrane. These morphologic findings suggest that annulate lamellae may be involved in the transfer of genetic material from the nucleus to the cytoplasm.

Adult↗
PubMed2025

SETD1B-mediated broad H3K4me3 controls proper temporal patterns of gene expression critical for spermatid development.

Epigenetic programming governs cell fate determination during development through intricately controlling sequential gene activation and repression. Although H3K4me3 is widely recognized as a hallmark of gene activation, its role in modulating transcription output and timing within a continuously developing system remains poorly understood. In this study, we provide a detailed characterization of the epigenomic landscapes in developing male germ cells. We identified thousands of spermatid-specific broad H3K4me3 domains regulated by the SETD1B-RFX2 axis, representing a previously underappreciated form of H3K4me3. These domains, overlapping with H3K27ac-marked enhancers and promoters, play critical roles in orchestrating robust transcription and accurate temporal control of gene expression. Mechanistically, these broad H3K4me3 compete effectively with regular H3K4me3 for transcriptional machinery, thereby ensuring robust levels and precise timing of master gene expression in mouse spermiogenesis. Disruption of this mechanism compromises the accuracy of transcription dosage and timing, ultimately impairing spermiogenesis. Additionally, we unveil remarkable changes in the distribution of heterochromatin marks, including H3K27me3 and H3K9me2, during the mitosis-to-meiosis transition and completion of meiotic recombination, which closely correlates with gene silencing. This work underscores the highly orchestrated epigenetic regulation in spermatogenesis, highlighting the previously unrecognized role of Setd1b in the formation of broad H3K4me3 domains and transcriptional control, and provides an invaluable resource for future studies toward the elucidation of spermatogenesis.

Male↗
PubMed1979

Genetic lesions induced by chemicals in spermatozoa and spermatids of mice are repaired in the egg.

Conclusive proof that the mouse egg is capable of carrying out repair of genetic lesions present in the male genome was obtained through dominant-lethal studies of chemically treated spermatozoa and spermatids and through cytological analysis of first-cleavage metaphases. The maximum difference in repair capability between stocks of females, found for isopropyl methanesulfonate treatment, was large; considerably smaller differences were found for ethyl methanesulfonate, triethylenemelamine, and benzo[a]pyrene treatments; and no difference was found for x-ray treatment.

Animals↗
PubMed1975

Sex chromosome meiotic drive systems in Drosophila melanogaster I. Abnormal spermatid development in males with a heterochromatin-deficient X chromosome (sc-4sc-8).

The meiotic drive chracteristics of the In(1)sc-4Lsc-8R/Y system have been examined by genetic analysis and by light and electron microscopy. sc-4sc8-/Y males show a direct correlation between nondisjunction frequency and meiotic drive. Temperature-shift experiments reveal that the temperature-sensitive period for nondisjunction is at meiosis, whereas that for meiotic drive has both meiotic and post-meiotic components. Cytological analyses in the light and electron microscopes reveal failures in spermiogenesis in the tests of sc-4sc-8 males. The extent of abnormal spermatid development increases as nondisjunction becomes more extreme.

Animals↗
PubMed1978

Polyribosomes associated with forming acrosome membranes in guinea pig spermatids.

Ribosomes, some of which are arranged in polyribosomal configurations, are attached to specialized regions of the acrosomal membrane in guinea pig spermatids. This finding indicates a new functional dimension for the acrosomal membrane, that of protein synthesis, and suggests that during acrosome formation, proteins of the acrosomal membrane or acrosomal contents need not be synthesized before or during passage through the Golgi apparatus.

Acrosome↗