Germinal Epithelial Cells Research Articles

The Cytosome of differentiating Cells in the Ovotestes of Slugs

ABSTRACT The distribution of ascorbic acid, alkaline phosphatase, and mitochondria has been followed during the differentiation of germinal epithelium cells into spermatogonia, oocytes, and nurse-cells in the ovotestes of slugs. All three substances appear in the cytoplasm of the oocyte and increase during its growth. Occasionally the oocyte nucleolus gives a positive test for ascorbic acid. The heads of the mature spermatozoa contain alkaline phosphatase. The cytoplasm of the germinal epithelium, spermatogonia, and spermatocytes occasionally gives’ a positive reaction for ascorbic acid. The development of the nurse-cells is accompanied by an increase in the size of the mitochondria. Attachment of the spermatids results in a decrease in size and number of the mitochondria in the nurse-cells. Alkaline phosphatase, ascorbic acid, and mitochondria show no significant change, either in form or quantity, in the indifferent cells of the ovotestis by which one could predict their destiny.

Oogenesis in the Desert Snail Eremina desertorum with Special Reference to Vitellogenesis

1. The histological structure of the ovotestis is briefly described. 2. The germinal epithelium gives rise to both categories of germ cells (male and female) as well as to the nurse cells. 3. During the differentiation of the germinal epithelial cell towards the germ line, it passes through a certain stage, ‘the progerminative indifferent stage’, before it is polarized either towards the male or female line. 4. A detailed description of the mode of differentiation of the progerminative indifferent cell into the earliest female element is given. 5. Mitotic multiplication of the early female elements never occurs. Nevertheless the diploid chromosome complement is represented by prochromosomes. 6. During the oocytic meiotic prophases, parasynaptic conjugation of the chromosomes is quickly followed by relational coiling of the synaptic mates, and the formation of the strepsitene double spirals. 7. The strepsitene double spirals give rise to the diplotene bivalents of the haploid count 28. 8. The steps of chromatin diffusion that lead to the construction of the typical oocytic germinal vesicle are described. 9. Changes in size, number, and stainability of nucleoli during oocytic growth are recorded. Extrusion of basiphil material from the nucleolus into the ooplasm is highly probable. 10. The mitochondrial granules at the beginning of the period of active oocytic growth form a huge zone to one side of the nucleus. Later they increase in number and widely scatter in the ooplasm. It is held (in favour of Harvey's view, 1929 and 1931) that mitochondria are probably concerned in the chemical synthesis of yolk from raw material provided in the ooplasm. 11. The Golgi bodies in oocytes are in the form of rods and not vesicular. In the early oocyte they form a group to one side of the nucleus. Eventually they disperse in the ooplasm either singly or in small typical complexes. Each of the latter is constituted of a few rods arranged end to end as if on the perimeter of an irregular circle. 12. The earliest yolk spheres (largely proteid) appear in the interior of the Golgi complexes or on the concave sides of the separate Golgi rods. 13. The Golgi rods become severed from the yolk spheres and migrate mainly towards the periphery of the oocyte where they collect in clumps. 14. The elements of the Golgi clumps become loaded with an unsaturated free fat. The original Golgi rod always preserves its identity and never transforms itself into fat.

Syndrome Characterized by Gynecomastia, Aspermatogenesis without A-Leydigism, and Increased Excretion of Follicle-Stimulating Hormone1

The syndrome under discussion begins during 11 adolescence and is characterised by gynecomastia and a very specific type of hypogonadism. This latter is almost entirely in respect to the function of the tubular tissue (germinal epithelium and Sertoli cells) while the function of the Leydig cells (growth of phallus and prostate and of sexual hair) remains relatively normal. Thus one finds bilateral gynecomastia, small testes, aspermatogenesis. evidence of normal to moderately reduced function of the Leydig cells, increased excretion of follicle-stimulating hormone (FSH), and usually a reduced excretion of 17-ketosteroids. During the last 4 years, 7 cases have been observed in the clinics of the Massachusetts General Hospital; studies on these patients and two additional private patients form the subject of this report. review of literature Although these cases are not uncommon, few reports are found in the literature, and to our knowledge, no author has grouped them together as a definite clinical entity.

The follicular cycle in the sexually mature thirteen‐lined ground squirrel (Citellus tridecemlineatus Mitch.)

AbstractThe germinal epithelium was studied in an effort to determine its role in postpubertal ovogenesis. Active and inactive areas of epithelium were observed regardless of the oestrous periods. The active areas, exemplified by numerous mitoses and a frequent stratification of the epithelium, are foci for egg cell production.Egg cells are produced from the germinal epithelium by: activation, migration and transformation of single germinal epithelial cells; migration and differentiation of nests of cells; ingrowths of cords of cells.Young ova in the cortex of the ovary are at first surrounded by a single layer of flattened follicular cells of germinal epithelial origin. In the subsequent development of the follicle stratified layers make their appearance. The zona pellucida appears as a well‐defined structure coincident with the stratification of the follicular layers.The follicular cavity develops as a split between the follicular cells at one side of the follicle. In the mature follicle the cavity is broad and contains liquor folliculi. The theca interna and externa are not distinguishable until the follicle is highly cellular.

The spermiogenesis of Succinea ovalis say, with special reference to the components of the sperm

AbstractAn investigation of the spermiogenesis of Succinea ovalis Say, a small terrestrial pulmonate, has revealed: 1) The germ cells are differentiated from indifferent germinal epithelial cells. In this form the germinal epithelium is a true epithelium, and not a syncytium. 2) Forty chromosomes are found in the spermatogonial divisions and twenty in the maturation divisions. 3) Early in spermiogenesis the proximal centriole penetrates through the spermatid nucleus and, with the oxychromatin, forms an intranuclear rod similar to that reported for certain prosobranches. The homology and significance of the rod are discussed. 4) Of the cytoplasmic structures, the mitochondria and the Golgi apparatus were followed through all stages of spermatogenesis. 5) At the maturation divisions the mitochondria are grouped into peculiar. thread‐like structures. Some of the mitochondria take part in the formation of the sheath around the axial filament of the spermatozoon, while the remainder are sloughed off with the cytoplasmic remnant. 6) The Golgi apparatus consists of a number of banana‐shaped rods closely grouped around the idiosome. Three to five Golgi rods are found in the spermatid stages. A portion of the Golgi apparatus and idisome (acroblast) forms the acrosome, and the Golgi remnant is discarded at the end of spermatogenesis. 7) In mature sperm both head and tail have a spiral structure. The origin and nature of the spirals are pointed out.

The formation of the sex glands and germ cells of mammals. III. The history of the female germ cells in the albino rat to the time of sexual maturity

AbstractThe entire ovary, including its germ cells, is produced by a local proliferation of peritoneal cells. The germ cells of the embryonic ovary grow, divide, become grouped into nests, pass through synaptic changes, and become primary follicles by three days after birth. At that time, growth of all the ova and follicles begins, and this results in a normal maturation, then a degeneration of all the ova by about thirty‐two days after birth; few, if any, of the original germ cells remain after this degeneration. About twenty‐three days after birth, there begins a great activity of the germinal epithelium in forming new ova, reaching its maximum between thirty‐six and thirty‐nine days, but continuing into the adult animal.The definitive ova of the adult are transformed peritoneal (germinal epithelial) cells formed anew during the late youthful and adult life. This occurs chiefly by a local enlargement of single germinal epithelial cells which become surounded by follicle cells and push into the ovary; there is also the production of ova from ingrowing cords of the surface layer of the ovary. The original germ cells pass through synapsis and other meiotic changes in late embryonic and early postnatal periods, but these all degenerate; synapsis cannot be distinguished later than three days after birth. But it is possible to follow, in young and adult ovaries, the transforming germinal epithelial cells into ova which pass through normal maturation and ovulation; therefore, these must be considered as true ova, which they are in fact, even though synapsis cannot be observed in their history.

Source of the Testicular Hormone.

In 1903 Ancel and Bouin1 published the theory that the interstitial cells of the testis (the cells of Leydig) produced the testicular hormone. The theory was based upon 4 main premises, as follows: Animals remain sexually active (a) after vasectomy, (b) when they possess only cryptorchid testes, (c) when their testes have been exposed to Roentgen rays and (d) when the only testicular tissue they possess is a graft. Under each of these conditions all germinal epithelium was reported absent while the interstitial cells were normal or hypertrophied. All 4 of these premises have been shown to be incorrect (see Oslund4, 5, 6, 7) and some germinal epithelium usually exists under each of the above conditions. Since both germinal epithelium and interstitial cells are present in hormone producing testes it has seemed impossible to designate which of these produces the hormone.It occurred to the writer that if a potent extract could be obtained from the epididymis this would offer strong presumptive evidence that t...

The Cytoplasmic Inclusions of the Germ-Cells

(1) In the germinal epithelial cell of Limnæa stagnalis a Golgi apparatus is present. It is excentric and lies around the archoplasm, consisting of a number of rods (chondrioplasts or dictyosomes, dittosomi). (2) In the progerminative oöcyte mitochondria appear at a very early stage, but it is not known whether they exist in the indifferent germinal epithelial cell. The mitochondria lie at first in the zone of the Golgi apparatus. (3) The rods of the Golgi apparatus divide by binary fission and keep growing in number. The archoplasm upon which they repose gradually becomes divided into regions; these regions again subdivide till each Golgi rod is discrete and provided with a small part of the archoplasm, which it partly embraces. As each Golgi rod divides transversely the urchoplasm does not divide. The latter only divides by binary fission after it has become studded with a number of rodlets. (4) The Golgi apparatus gradually, from its excentric position, spreads completely throughout the egg cytoplasm, and in the full-grown oocyte is evenly distributed here and there in all parts of the egg cytoplasm. No segregation into special regions was noticed. (5) The mitochondria, from their excentric position near the Golgi apparatus, grow, divide, and spread evenly throughout the cytoplasm. The mitochondria are not all the same size; this is apparently due to the fact that some granules grow larger and more quickly than others. (6) While the egg mitochondria grow much larger than the spermatid mitochondria, it has been shown that the individual Golgi batonette or rodlet never grows beyond a certain size. The difference between the Golgi apparatus of a young oöcyte and a full-grown ovum lies, not iu the fact that the Golgi rods of the latter are individually very much larger (if at all) than those of the former, but mainly in the fact that the rods have increased enormously in number by binary fission. The individual Golgi rodlet of spermatid, young and old oöcyte are approximately subequal in size. (7) Deutoplasmagenesis, or the formation, of yolk, does not begin very early; the first yolk-discs make their appearance after the Golgi elements and mitochondria have progressed far in the process of spreading throughout the growing oöcyte. The yolk-discs do not appear in any special region of the cytoplasm, but eventually become evenly spread out. The discs at first are very small, and later grow some two or three times larger than the largest mitochondria. In Flemming-without-acetic (overnight) + iron-alum hæmatoxylin, yolk goes dark brownish-green, mitochondria black. (8) Towards the end of oögenesis the cytoplasm gradually becomes filled with vacuoles of a fluid nature. These leave a coagulum on fixation, but most of the vacuole is empty. The granules in the cytoplasm only abnormally lie in these vacuoles; yolk, Golgi elements and mitochondria lie in the trabeculas between the vacuoles.