Primitive Germ Cells Research Articles

GERM CELL TUMORS OF THE OVARY

This group of ovarian neoplasms is composed of a number of histologically different tumor types and embraces all the neoplasms considered to be ultimately derived from the primitive germ cells of the embryonic gonad. The concept of germ cell tumors as a specific group of gonadal neoplasms has evolved in the last three decades. It is based on (1) the common histogenesis of these neoplasms, (2) the relatively frequent presence of histologically different neoplastic elements within the same tumor mass, and (3) the presence of histologically similar neoplasms in extragonadal locations along the line of migration of the primitive germ cells from the wall of the yolk sac to the gonadal ridge,332 as well as on the remarkable homology between the various tumors in the male and the female.

Comparative studies of normal and neoplastic ovarian germ cells: 1. Ultrastructure of oogonia and intercellular bridges in the fetal ovary.

Electron microscopic studies were performed on human fetal ovaries to gain insight into the process of mitotic proliferation in developing germ cells. Three stages of germ cell differentiation are present during the early gestational period: primitive germ cells, oogonia, and oocytes. Oogonia, representing the mitotic stage of differentiation, are the predominant cell type present between 9 and 12 weeks' gestation and then progressively decrease in number as a result of transformation into oocytes in meiosis and degeneration. Mitotic division of oogonia, which is extensive during the late first and early second trimesters, is characterized by incomplete separation and persistence of intercellular bridges between germ cells. Intercellular bridges were found in large numbers from 10 weeks until the time of follicle formation at midgestation. The bridges contained microtubule arrays consistent with remnants of the spindle apparatus. The findings support the role of germ cell bridges in maintaining coordination of proliferative activity during the early developmental period.

Comparative studies of normal and neoplastic ovarian germ cells: 2. Ultrastructure and pathogenesis of dysgerminoma.

A series of dysgerminomas of the ovary was examined by electron microscopy and the findings were compared with germ cells in the normal developing ovary. The ultrastructural characteristics of the neoplastic cells, including prominent reticular nucleoli and sparsely distributed cytoplasmic organelles, indicated a close resemblance to oogonia present in the fetal ovary. Occasional cells had localized collections of glycogen, resembling primitive germ cells, but the irregular ameboid appearance and eccentric nuclear location characteristic of cells in the early stage were not seen. Ultrastructural features of oocyte differentiation, such as synaptinemal complexes and perinuclear arrangement of mitochondria, were not found in any of the tumors. Intercellular bridges, a frequent finding at the oogonial stage in the normal ovary, were absent in all of the tumors. The lack of intercellular communication could be responsible for uncontrolled mitotic division leading to germ cell neoplasia.

Immunohistochemical demonstration of placental alkaline phosphatase in various states of testicular development and in germ cell tumours.

Immunohistochemical localization of placental alkaline phosphatase (PlAP) has been performed on eighty-two samples of normal (embryonic, fetal, infantile or adult), cryptorchid or tumorous testicular tissue. The isoenzyme could be demonstrated at the cell membrane of primitive, embryonic germ cells but not in other normal tissues. In-situ carcinomas and seminomas were positively stained in 93% and 94% of cases respectively. The percentage of positivity decreased with tumour differentiation. It is suggested that PlAP is a marker of primitive germ cells and that it reappears in germ cell neoplasms by gene derepression.

Initiation of oogenesis in the human fetal ovary: Ultrastructural and squash preparation study

Ovaries from 27 human fetuses at ≤ 12 weeks' gestational age were examined with electron microscopy and squash preparation studies. The findings demonstrated that meiosis begins in the fetal ovary between 11 and 12 weeks of age. This is several weeks after gonadal sex differentiation, which can be recognized in the testis at 6 weeks. Ovaries at earlier ages included primitive germ cells and oogonia. With advancing fetal age, mitotic activity and germ cell degeneration became increasingly evident. Preleptotene cells were found as early as 9 to 10 weeks, suggesting that meiotic capacity is present soon after gonadal sex differentiation but further progression into meiosis is delayed until some specific inductive influence is exerted.

Pilomatrixoma (Benign Calcifying Epithelioma of Malherbe)

A 24-year-old white man had a large subcutaneous discolored tumefaction of the right lower lid, successfully treated by two separate incision and drainage procedures. Microscopic appearance initially suggested basal cell epithelioma, but further studies provided a correct diagnosis of pilomatrixoma (calcifying epithelioma of Malherbe). This lesion probably represents aberrant primitive germ cells differentiating towards a hair matrix cell. Basaloid and squamoid (shadow) cells with or without focal calcifications in shadow cell areas are typical, and the clinical presentation is also highly suggestive of pilomatrixoma.

Ultrastructural study of intracranial yolk sac tumor: with special reference to the oncologic phylogeny of germ cell tumors.

Ultrastructural studies of yolk sac tumors (YST) have generally demonstrated the resemblance of this neoplasm to the primitive human yolk sac. However, these studies have failed to explain the common occurrence of mixed germ cell tumors with yolk sac elements. This report describes the ultrastructural features of a suprasellar YST. This tumor resembled those previously described. Also demonstrated, however, was the presence of primitive germ cells admixed within the neoplasm. A new schema is proposed based on these observations for the interrelationship of germ cell tumors, which may explain the common occurrence of mixed germ cell tumors.

Response of the Sertoli cell and stem germ cell to 60Co gamma-radiation (dose and dose rate) in testes of immature rats.

Gamma-radiation effects (dose and dose rate) on the Sertoli cells and stem cells of the germinal line in immature rat testes were examined. Prior to Day 4 of postnatal development, the gonocyte or primitive germ cell was the most radiosensitive cell in the testis. From Day 4 to approximately Day 15 the Sertoli cell was the most critical element, and thereafter the stem cell was of first importance. A dose of 100 rads irreversibly reduced the number of Sertoli cells to 63 percent of control. Of the ages tested beyond Day 2, the 9-day testis was most severely affected. It was estimated that a dose of 400 rads would reduce sperm output of the 9-day testis to 21 percent of control. After Day 4 and prior to Day 20, 300 rads produced a permanent decrement in the stem-cell population. Six hundred rads are required to produce this effect in the adult. Dose rate was an important mediator of the radioresponse of both Sertoli and germ cells.

The fine structure of possible carcinoma-in-situ in the seminiferous tubules in the testis of four infertile men.

An abnormal morphology of germ cells was found in the seminiferous epithelium of four infertile men, three of whom developed a carcinoma of the same testis. The ultrastructure of the abnormal germ cells from the different patients were compared and found to be almost identical. The fine structure of the cells was also compared with that of the normal pre‐ and postpubertal germ cells described in the literature. We found that the abnormal germ cells were similar to the former although they also possesed several malignant features as regards the size and shape of nucleus, nucleolus and the density of cytoplasmic organelles. The ultrastructure of the Sertoli cells was compared with that of normal pre‐ and postpubertal Sertoli cells described in the literature. Morphologically they seemed to be normal postpubertal Sertoli cells. The findings indicate that the abnormal cells represent a carcinomain‐situ of rather primitive germ cell origin.

Differentiation and Radioresponse (Dose and Dose Rate) of the Primitive Germ Cell of the Bovine Testis

Two distinct forms of the gonocyte, or primitive germ cell, were delimited in the testis of the prepuberal bull. The most primitive of these, the type I gonocyte, gives rise through its mitoses to ...

Ultrastructural observations on germ cells in human fetal ovaries

Ovaries of 18 human fetuses from 7 to 20 weeks of age were examined with the electron microscope. Germ cells were observed at three distinct stages of maturation. Between 7 and 9 weeks, large, amoeboid-appearing primitive germ cells were scattered as single cells throughout the ovarian parenchyma. From 10 to 12 weeks, groups of dividing oogonia were observed. Oocytes in various stages of meiotic prophase were present from 12 weeks onward. The identical appearance of germ cells in a given area indicated the presence of local synchronization of development, attributed to the presence of intercellular bridges. During the period of oocyte maturation, there was extensive degeneration of germ cells. Cellular debris resulting from the degenerative process was phagocytized by granulosa cells. The number of granulosa cells containing phagocytized material correlated with the number of degenerating germ cells present. Both reached a peak between 16 and 20 weeks, at the time when the first primordial follicles began to appear.

Ultrastructure of germ cell development in the human fetal testis.

Electron-microscopic examination of the human fetal testis between 10 and 20 weeks gestation reveals the presence of two distinct cell types within the tubules: Sertoli cells and germ cells. The latter are distinguished by their spherical shape, smooth nuclear membranes, globular mitochondria and paucity of cytoplasmic organelles. The gonocytes, or primitive germ cells, occur as single cells in the central portions of the tubules. Their chromatin is finely granular and evenly dispersed. Nucleoli are centrally placed and of uniform electron density. Various stages in the migration of gonocytes to the tubular periphery are indicated by the extension of cytoplasmic processes toward the basal lamina. Bands of microtubules are present within the processes. Spermatogonia are arranged in pairs and groups at the tubular periphery. They lack the nucleolar and mitochondrial characteristics of adult spermatogonia. Except for slight changes in chromatin density and nucleolar structure, the fetal spermatogonia retain the ultrastructural characteristics of gonocytes. Intercellular bridges connect adjacent spermatogonia. Degeneration affecting large numbers of germ cells, but primarily gonocytes, begins with nuclear infolding and chromatin condensation and eventually involves both nuclear and cytoplasmic structures. The degenerated cells are removed by phagocytosis by adjacent Sertoli cells. Large phagosomes are present in the cytoplasm of many of the Sertoli cells.

The ontogeny of sperm specific lactate dehydrogenase in mice.

AbstractTestes of sexually mature mice (Mus musculus) contain a unique lactate dehydrogenase isozyme associated with the spermatozoan cell. This isozyme differs in subunit composition and reactivity to the substrate DL‐α‐hydroxyvalerate when compared to the usual five isozymes found in other tissues. It has been termed LDH‐X and has the same mobility as LDH‐5 when subjected to electrophoresis on standard polyacrylamide gels. This enzyme first appears during development at the time spermatocytes first mature in the testes.From the time of birth until sexual maturity is reached the specific activity of LDH in testes extracts does not change appreciably. When the mice have reached the weight of 6.5 to 7.5 g with a testes weight of 20 mg, which is equivalent to an age of 15 to 17 days postpartum, LDH‐X appears. It is at approximately this time that the first differentiative division of the primitive germ cell, the spermatogonium, occurs. For the next period of time, 15–20 days, the testes grow and differentiate at a rapid rate and during this same period the specific activity of the sperm LDH also increses.Histochemical evidence indicated that activity of LDH‐1, 2, and 3 is highest in the interstitial cells while LDH‐X activity is restricted to the cells that are close to the lumen of the testicular tubule.

Mammalian testes in organ culture

Testes of 14-day-old rats were grown as organ cultures for periods of up to 6 months. The effect of various culture media, gas phases, pH's and incubation temperatures was investigated. Tubular structure with healthy Sertoli cells and mitoses was well maintained under various culture conditions, including growth in chemically defined medium. Spermatocytes survived approximately four weeks without differentiating into spermatids. A cell type, resembling primitive germ cells of younger animals, consistently appeared in seminiferous tubules on the fourth day of culture. Since these cells are not normally observed in the testes of 14-day-old rats, their possible origin in culture is discussed.

EFFECTS OF NEONATAL GAMMA IRRADIATION ON HORMONE PRODUCTION AND SPERMATOGENESIS IN TESTIS OF THE ADULT PIG.

Summary. The morphogenesis of the Leydig cells and germ cells of the pig during the first 130 days after birth is described in relation to estimates of cellular radiosensitivity. Boars aged 1 to 30 days were exposed totally to 200 r of gamma rays and the effects on the Leydig cells and germ cells were determined before and after puberty. The number of gonocytes (primitive germ cells) declined to 10% of the control values by Day 30 after irradiation, but at Day 60 some recovery was evident. Postpubertally, an average of 23% of the seminiferous tubules seen in transverse section in the irradiated testes exhibited radiation damage which was presumably permanent. Average sperm production was 47% of the control value. Increased numbers of crenated nuclei and a delay in morphogenesis were noted among the Leydig cells before puberty. Urinary steroid output of the irradiated boars equalled or exceeded that of the non-irradiated boars and it is assumed that 200 r of gamma rays effected no permanent damage among the Leydig cells.

The histogenesis of the endocrine organs of the viviparous lizard, Xantusia vigilis

The embryology and histogenesis of the pituitary, thyroid, parathyroid, thymus and ultimobranchial glands, the pancreatic islets, adrenal glands, and the gonads were studied in the viviparous lizard, Xantusia vigilis. The epithelial portion of the pituitary gland arises as a single diverticulum (Rathke's pouch) which subdivides into oral and aboral lobes. The aboral lobe develops into the pars intermedia and a very small portion of the pars distalis, and the oral lobe forms the greater part of the anterior pituitary. Basophil cells differentiate in the pars distalis at the 10-mm stage (about halfway through development), and acidophil cells at the 21 mm (about 2 weeks before birth). The follicles of the thyroid contain thin colloid at the 7–8-mm stage (about 1 week prior to the differentiation of pituitary basophil cells). The follicular cells appear most active during the last third of gestation. The parathyroid arises from the entoderm of the third visceral pouch and develops in the concavity of the bifurcating carotid artery. Fine acidophilic granules appear in the cytoplasm at the 8-mm stage. The thymus develops from the second and third pouches, and the constituent cells appear thymocytelike by the 7-mm stage. The ultimobranchial body arises unilaterally from a left diverticulum posterior to the fourth arch and develops into a large mass of epithelioid cells containing abundant acidophilic granules. The pancreas arises from a single dorsal and two ventral diverticula of the foregut, the dorsal forming the splenic portion and the left ventral most of the head. Cells with amphophilic granules (“muddy” cells) appear by the 3–4-mm stage among the cells of the cords derived from the dorsal rudiment. Alpha and beta cells appear by the 7–8-mm stage. Both coelomic epithelium and underlying mesenchymal cells proliferate to form the gonadal ridge in the 2–3 mm embryo. Primitive germ cells at first are scattered throughout the prospective gonadal ridge and adjacent tissues; later they become incorporated within the stroma of the enlarging gonad. A single medullary tubule is formed in the developing gonad of each sex at about the 5–6-mm stage. Sexual differentiation occurs during the 6.5–7.0-mm stage. The ovary only briefly retains rudimentary medullary tubule material, but the testis retains a small patch of cortical gonocytes until birth. Typical interstitial cells are not observed in either gonad. The Sertoli cell cytoplasm in the testis appears secretory and may be the source of fetal androgen. Interrenal tissue is derived from the region of the intermediate mesoderm, and forms a large mass of cells containing osmiophilic droplets by the 3-mm stage. Medullary elements form a dorsal cap over the interrenal cells and contain fine osmiophilic granules by the 8-mm stage.

Effects of Prenatal Gamma Irradiation on the Germ Cells of the Male Pig

pattern of porcine prenatal testicular development, and, where possible, germ-cell radiosensitivity is related to these. The first evidence for gonocyte (primitive germ cell) radiosensitivity was noted in testes irradiated at 35 days of gestation, but a marked effect on the gonocyte population was not evidenced until day 50. Germ-cell radiosensitivity continued at the same level throughout the remaining portion of gestation studied (to 90 days). Initiation of pronounced gonocyte sensitivity (day 50) was shown to be correlated with the definitive organization of the sex cord. Comparisons between rat and pig gonocyte radioresponses are drawn, and the possibility of a qualitative difference in their respective germ-cell populations is discussed. (auth)

EFFECTS OF GAMMA-IRRADIATION ON THE PRIMITIVE GERM-CELLS OF THE PREPUBERTAL BOVINE TESTIS.

SummaryPost-natal male Hereford calves aged 1 to 150 days were exposed to a 200 r whole-body dose of gamma-rays and castrated at 30, 60, or 210 days after irradiation.The quantitative histological analysis revealed that the primitive bovine germ-cell is most radiosensitive during the post-natal period which extends from birth to approximately 70 days old. A lesser sensitivity was apparent at 80 to 105 days, and relatively minor damage was produced from 120 to 150 days post-natal.Changes in germ-cell radiosensitivity were shown to be correlated with quantitative and qualitative alterations within the developing germ-cell population.

Effects of Continuous Radiation on Chick Embryos and Developing Chicks

The following description of the effects of lethal and sublethal continuous radiation on the bone marrow, lymphoid tissue, and blood of chick embryos and developing chicks, by means of the isotope P32, is the second part of a study embracing all the tissues in these subjects and including measurements of the localization of the agent within the tissues (2). The findings described in the first report were briefly as follows: Radiation caused an over-all growth retardation resulting in small but well proportioned birds. Both testes and ovaries were very radiosensitive, the primitive germ cells being the most sensitive element. The sper-matogenic cells of the testes remained extremely sensitive to radiation throughout their development, while the ova became more radio-resistant as they matured. Bone growth was retarded by radiation. The cartilage cells of the epiphyses were much more radiosensitive than the osteoblasts and osteoclasts. After irradiation ceased, the histologic changes were reversible and the bones regained a normal histologic structure but remained dwarfed. Materials and Methods P32 combined as KH2P04 was injected into eggs which were incubated under the usual conditions of 38-39° C. and 70–80 per cent relative humidity. The incubated eggs were divided into groups according to the amount and time of injection. Injections varied in amount from 47.5 μc to 300 μc. At regular intervals embryos and birds were selected at random from each group, killed by decapitation, and studied histologically. In order to study radiation effects later in the course of development, subcutaneous injections of approximately isotonic solution of P32 as KH2PO4 were made into twenty-four chicks after hatching. Doses varied from those producing no histologically demonstrable effects to those causing death. The smallest dose was 115 μc, the largest 3,696 μc. Effect of Radiation on Bone Marrow Radiation had its crucial effect on the blood-forming tissues. The concentration of the radioactive substance within the bones caused heavier irradiation of bone marrow than of other tissues. Hematopoiesis takes place during the early part of incubation, largely in the blood islands of the vitelline sac. Between the tenth and twelfth day of incubation, the bone marrow begins its hematopoietic function, and several days before hatching it is the chief source of red blood cells and granulocytes. Blood-forming marrow develops in all bones, but the greatest number of hematopoietic cells is found in the long bones and vertebral bodies. The liver and spleen do not appear to be of importance in hematopoiesis in the embryo or young chick. Erythrocytes form within endothelial-lined sinuses of the bone marrow, apparently in communication with the circulation, and enter the circulation when they are mature. Granulocytes are formed in the intersinusoidal spaces and after reaching maturity migrate into the circulation.

Observation, on the Breeding and Development of the viviparous fish, Heterandria formosa

ABSTRACT A short account is given of the breeding habits of Heterandria formosa in an aquarium. The ovary and the mature ovum are briefly described, the noteworthy feature of the ripe ovum being the small quantity of yolk. 8. Degeneration of ova is found to be a common occurrence in unfertilized females, and to a less extent in those full of developing embryos. The method for ensuring the fertilization of the egg within the follicle is portrayed. Over the area where the spermatozoa have entered the cells of the ovarian epithelium and those of the follicle form a solid plug which eventually disrupts to enable the fully developed embryo to escape into the cavity of the ovary. It is characteristic of early development that the egg is encircled by a unilaminar ectoderm before there is any visible differentiation into endoderm and mesoderm. Owing to the scarcity of yolk only a few periblast cells arise and no syncytial layer is formed. The primitive-germ cells are visible at an early stage within the apparently undifferentiated mesendoderm cells. A striking feature is the large size of the pericardium and its growth upwards as a pericardium hood which completely surrounds the head region of the embryo. Over the walls runs a network of blood-vessels from which the maternal capillaries become eventually separated by only an attenuated layer of protoplasm. Both respiration and nutrition are effected through the follicle. A remarkable specialization is the development of a urinary bladder which expands into a thin-walled vesicle of enormous dimensions, finally occupying almost the entire area formerly filled by the pericardium and the yolk-granules. The development of Heterandria is compared with that of other viviparous fishes. The significance of the unusual features in early and late development is discussed and some comparisons are made with the conditions in higher vertebrates.