Primary germ cells

Moran CA, Suster S, Przygodzki RM, Koss MN. Primary germ cell tumors of the mediastinum II. Mediastinal seminomas—a clinicopathologic and immunohistochemical study of 120 cases. Cancer. 1997 80 691-698. 

Extratestlcular Primary Germ Cell Tumors and Metastatic Germ Cell Tumors... 

Within the cranial vault, 95% of primary germ cell tumors are found along the midline in the pineal and suprasellar regions, especially the former. About 10% involve both regions, and 25% arise in the suprasellar cistern. The mixed germ cell tumor and lymphoma (ger-lymphoma) has only been seen in the sella turcica. Germ cell tumors rarely involve spinal cord or peripheral nerve. ... 

Comparison of the Overall Composition of Cell Wall Preparations. As can be seen from Table I, cell wall preparations showed a significant difference in their polymer composition. The endosperm cell walls resembled primary walls, since they were virtually free of lignin but rich in pectic substances. On the other hand, the cell wall preparations obtained from the caryopsis coat and the aleuron tissue were highly lignified, and their pectic content was very low. The germ cell wall showed a somewhat intermediate composition between these two types, probably reflecting the fact that it consists of several different tissues. 

Spermatogonium. An undifferentiated germ cell of a male, originating in a seminiferous tubule and dividing into two primary spermatocytes. 

Unlabeled Uses Adrenocortical, bladder, cervical, endometrial, prostatic, testicular carcinomas Ewing s sarcoma multiple sclerosis non-small cell, small cell lung cancer organ transplant rejection osteosarcoma ovarian germ cell, primary brain, trophoblastic tumors rheumatoid arthritis soft tissue sarcomas systemic dermato-myositis systemic lupus erythematosus Wilms tumor... 

In the humans, the primordial germ cells are differentiated from about the sixth week of gestation and are consequently susceptible from then onward. In the female, production of the primary oocytes, which involves the first meiotic division, occurs in fetal life. These primary oocytes do not mature into ova until puberty, with the second meiotic division yielding one ovum from each primary oocyte (Fig. 6.48). 

Each cytogenetic test system has advantages and disadvantages. For instance, if a very simple determination of a compound s ability to produce chromosomal aberrations in vivo is desired, a bone marrow assay is probably simplest and least expensive. If, however, genetic hazards to future generations are of primary concern, assays of germ cells would be more appropriate. In in vitro assays of peripheral lymphocytes or cell lines, the cells can be made synchronous or fairly synchronous. 

Some or all events leading to sex-chromosome loss or nondisjunction are either not inducible in or not recoverable from some of the germ cell stage.378 However, very few chemicals have been tested, and none in all germ cell stages. Sex-chromosome loss has been shown to be induced by triethylenemelamine in spermatids and spermatozoa, 55 by isopropyl methanesulfonate in primary oocytes within 6 wk of being ovulated,138 and by hycanthone methanesulfonate in primary oocytes within 1 wk of being ovulated.38 ... 

The ovaries perform two major functions (i) the storage, maturation, and expulsion of healthy haploid germ cells (i.e., oocytes) for fertilization, and (ii) the synthesis and secretion of hormones to prepare the reproductive tissues for the establishment and maintenance of pregnancy, to properly regulate gonadotropin secretion from the hypothalamic-pituitary axis, to induce appropriate sexual behaviors, and to provide lactation. The two primary functional units in the ovaries are the maturing follicles and the corpora lutea. 

The blastocyst is a hollow, fluid-filled ball of approximately 1000 cells. The cells that form the outer layer are referred to as trophoblasts and will ultimately develop as extraembryonic tissues (e.g., placenta), while the cells of the inner cell mass are omnipotent (i.e., stem cells) and form the embryo. Depending on the species, the blastocyst arrives at the uterus within 5-10 days of fertilization, whereupon it hatches from the zona pellucida and implants into the uterine wall, which has been preconditioned by ovarian-derived steroid hormones (see Chapter 33). Shortly after implantation, the inner cell mass undergoes gastrulation to form a trilaminar embryo composed of three primary germ layers, the ectoderm, mesoderm, and endoderm. 

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