Testicular structure and spermatogenesis of short mackerel, Rastrelliger brachysoma (Bleeker, 1851) in Upper Gulf of Thailand

Testicular structure and spermatogenesis of short mackerel, Rastrelliger brachysoma (Bleeker, 1851) (Teleostei: Scombridae) was first investigated. The testicular parenchyma was a lobular organ, which was classified as an unrestricted spermatogonial type. The classification of spermatogenetic stage could be classified into six stages based on the pattern of chromatin condensation and other characterizations at the light microscopic level. These six stages included the primary and secondary spermatogonium, primary and secondary spermatocyte, spermatid and spermatozoon. The spermatogenesis could also be classified into another four stages based on the nuclear and cytoplasmic characterizations at the ultrastructural level. Spermatogonium was the early germ cell. It underwent a series of mitotic division to reach the primary spermatocyte. Secondary spermatocyte was shown as the heterochromatin surrounding the nuclear membrane, which was rarely seen within seminiferous lobules. Stages during the spermatids differentiation comprised of the early, intermediate and late stages which are under the degree/change of chromatin condensation. Finally, the spermatozoon was revealed as the aquasperm primitive type. It was composed of an oval head without an acrosome, a short mid-piece consisting of two basal bodies (proximal and distal centrioles) and a long flagella tail without lateral fins. The axonemes of classical form with 9+2 microtubules were presented in the flagellum.

Impaired chromosome segregation results in sperms with excess centrosomes in emb-27APC6 mutant C. elegans

The anaphase-promoting complex (APC) is a major regulator of chromosome segregation and is implicated in centriole engagement, whose de-regulation causes abnormal number of centrosomes. The emb-27 gene in C. elegans encodes a subunit of APC. The paternal emb-27 mutant was reported to show cell division with multiple furrows, suggesting the presence of excess centrosomes. In this study, we examined the number of centrosomes and the mechanism underlying de-regulation of centrosome number in emb-27 mutants. Our observations indicated excess centrosomes in emb-27 sperms, which resulted in zygotes with excess centrosomes. Further, the secondary spermatocyte of emb-27 produced reduced number of spermatids, which is likely the direct cause of the excess number of centrosomes per sperm. We propose that a chromosome segregation defect in emb-27 induced centrosome separation defect, resulting in reduced number of buds. Additionally, treatment with cytoskeletal inhibiting drugs indicated presence of three kinds of forces working in combination to move the centrosomes into the spermatids. The present study suggested a novel role of microtubule in the budding cytokinesis of spermatocytes.

Morphological characterization of the gonads of bullfrog tadpoles (Lithobates catesbeianus)

Introduction: This work describes various aspects of early gonadal development of female and male in pre-metamorphic tadpoles (Lithobates catesbeianus) at Gosner stage 25. Materials and Methods: Ovaries and testicles were prepared for routine light microscopy for morphological study and for acridine orange technique fluroescent microscopy for observation of RNA cytoplasm activity. Results: The results showed that female gonads at Gosner stage 25 predominated primary and secondary oogonias, as well as primary, secondary and tertiary oocytes. The developing testicle presented primary spermatogonia (I or A) and secondary spermatogonia (II or B), and as well as primary and secondary spermatocyte. All this cell phases were morphologically characterized and the cell sizes measured. In pre-metamorphic testes the somniferous duct are not developed and the vasa deferentia is opened. Conclusion: At this point, it was possible differentiate ovary from testes does not for the gonadal cells, but for the general anatomy of the organs, being the ovary a spheroid structure and the testicle an elongated tubule.

Spermatogenesis and spermiogenisis in the testes of local Iraqi breed cat (Felis catus)

The seminiferous epithelium of the testes of cat consists of two groups of cells; Spermatogenic cells and Sertoli cells. The interstitial areas are filled with Leydic cells, blood and lymph vessels, and connective tissue. Germ cells in the Spermatogenic process of the testis of cat can be classified into ten steps, based on the pattern degree of nuclear chromatin condensation. Primary spermatogonia contain large spherical nuclei with mostly euchromatin. Spermatogonia proliferate to give rise to spermatogonia type –A; Intermediate or type-I spermatogonia, and spermatogonia type-B. Type–B spermatogonia yield primary spermatocyte at the end of mitosis. The primary spermatocyte is transformed into secondary spermatocyte during meiosis I. These cells are converted into spermatid during meiosis II. Metamorphosis of spermatids shows: Golgi step, Cap step, Acrosomal step, Maturation step.

Testicular Effects of Bis (2-Methoxyethyl) Ether in the Adult Male Rat

The onset of testicular pathology in the rat and possible recovery over an 8-week period were evaluated after the administration of up to 20 daily oral doses of bis(2-methoxyethyl) ether (diglyme) at 5.1 mmol/kg bw (684 mg/kg bw). Primary and secondary spermatocyte degeneration and spermatidic giant cells were observed after six to eight treatments. In addition, the testes-to-body weight ratio was significantly reduced by the tenth day of treatment and continued to be depressed eight weeks after discontinuation of the treatment. Testicular LDH-X activity, a pachytene spermatocyte marker enzyme, was significantly decreased in animals by the eighteenth day of treatment with diglyme.

Phase-contrast and electron-microscopic observations on a membranous complex in primary spermatocytes of the mouse

A prominent cytoplasmic inclusion present in living mouse primary spermatocytes has been observed by both light and electron microscopy. It began to form at prometaphase and continued to increase in thickness and length as the cells developed. By metaphase it was a distinct sausage-shaped boundary that enclosed a portion of the cytoplasm between the spindle and the cell membrane. At the end of metaphase, the inclusion reached its maximum length. At telophase, it was divided between the daughter secondaries. The inclusion persisted as a circular contour in the interphase secondary spermatocyte. Electron microscopy of the same cultured cells that were previously observed with light microscopy revealed that the inclusion was a distinctive formation of membranes. It consisted of agranular cisternae and vesicles, and was therefore a membranous complex. Many of the smaller vesicles in the membranous complex resembled those found in the spindle. The cisternae in the membranous complex were identical to the cisternal endoplasmic reticulum of interphase primary spermatocytes. Nevertheless, the organization of vesicles and cisternae into the membranous complex was unique for the primaries in division stages, since such an organization was not present in their interphase stages.

OBSERVATIONS OF CENTRIOLE FORMATION IN MALE MEIOSIS

Centriole formation in male meiosis of the hyrax, Heterohyrax syriacus, and the Berdmore palm squirrel, Memetes berdmorei, was investigated by serial section analysis of selected regions of the seminiferous epithelium and isolated meiotic cells. Two periods of centriole formation were observed, a first in cells in transition between zygotene and pachytene and a second in the secondary spermatocytes. The duplication events before each meiotic division insured the presence of a centriolar duplex at each division pole. The parental member of each duplex of the second division was closely associated, at its distal end, with the plasma membrane. This orientation was established in the secondary spermatocyte and persisted until the completion of telophase II. Subsequently in early spermatids, each duplex assumed a characteristic orientation adjacent to the nucleus.

Germinal differentiation of the stem cell in Hydra fusca: a model system

The consecutive stages in the differentiation of the stem cell to the spermatozoon were characterized based on time of appearance, cytology, volumes, and spatial distribution. In the first few days the stem cells (128 μ3) enlarged and entered a phase of intense mitosis. In these cells or primary spermatogonia (220–1140 μ3), the cytoplasm was intensely basophilic, the DNA dispersed as a fine meshwork, and a large nucleolus was present. In secondary spermatogonia (123 μ3), noted after 14 days, the DNA was organized in small granules and the nucleolus reduced in size. The primary spermatocyte (122 μ3) was seen by 16 days; its cytoplasm was weakly basophilic, the nuclear DNA appeared granular, and a nucleolus was absent. After meiosis I, the secondary spermatocyte (60 μ3) immediately entered meiosis II. The spermatids (31 μ3), noted by 18 days, lacked a nucleolus and had dense irregular masses of DNA scattered throughout the nucleus. Spermatozoa, seen after 20 days, consisted of a cone-shaped head, a middle piece containing four large mitochondria, and a long flagellum. All these cell types were distributed sequentially within the testis according to their chronological order of appearance. The use of spermatogenesis as a model system to study cell differentiation and control requires further methodological developments and biochemical information.

The Structure of the Germinal Epithelium of the Fowl Testis with Speical Reference to the Presence of Multinuclear Cells

The effects of histological fluids on the cells of the germinal epithelium of the fowl testis have been studied with a view to confirming the fact, evident from studies of living cells, that the formation of multinuclear cells in the process of spermatogenesis is a normal occurrence. It is considered that in the most rapidly dividing germ-cells the cytoplasm is not in a very concentrated state and the usual methods of fixation, by diffusing fluids into the testis, result in disruption of the cytoplasm, especially in multinuclear cells. Methods of fixation were selected which preserved the latter in sufficient numbers to follow their development. It appears that the two secondary spermatocyte nuclei, produced after the first meiotic division of the primary spermatocyte, tend to remain together forming a binucleate cell, which becomes four-nuclear after the second meiotic division. These nuclei, now haploid, are capable of frequent multiplication within the cell before each, then designated a spermatid, eventually becomes transformed into a spermatozoon. The significance of post-meiotic multiplication is discussed.