Studies on the growth sequence of follicles in mature mice four to six months old were conducted by giving the three injections of 16 muCi tritiated thymidine (3H-T)/gm body weight at four hour intervals over a period of eight hours. Subsequent radioautographic analysis on ovaries obtaine d 1,3,5,9, and 17 days after the last injection showed an overall follicle growth time of 17 to 19 days. The duration of the different follicle stage times were also estimated from radioautographic data. Intense 3H-T incorporation was noted in the developing antra and zona pellucida of follicles of animals sarcrificed on e and three days after treatment suggesting that these areas serve as precursor storage sites during development. Oocytes of follicles in early antrum formation also showed juxtanucleolar 3H-T incorporation concomitantly with rapid and massive oocyte and follicular growth. The findings further indicate that the earliest follicular cells surrounding the oocyte originate at some distance from the developing primordial follicle.
Intranuclear and cytoplasmic annulate lamellae were studied in grasshopper spermatocytes (Melanoplus) with the electron microscope. Although cytoplasmic annulate lamellae were observed in all three species examined, intranuclear annulate lamellae were found in only one species. The intranuclear annulate lamellae encompass certain nuclear material adjacent to the nuclear envelope forming a vesicle that is extruded into the spermatocyte cytoplasm. In this same species, cytoplasmic annulate lamellae are seen contiguous with granular masses of varying size. These structures were noted as being morphologically indistinguishable from the "yolk nuclei" of dragonfly oocytes (Kessel and Beams, 1969; Kessel, 1973).
Adult mice were pulse labeled with tritiated thymidine [3H]TdR and killed 9 hr later. A low level incorporation of [3H]TdR into the nuclear DNA of Purkinje neurons was found in autoradiographs. Enzymatic digestions with DNase and with RNase in combination with autoradiographic grain counts indicate that a portion of nuclear DNA is not stable in the Purkinje nucleus. These results are discussed in light of reports of the stable nature of DNA in Purkinje neurons of adult mice.
Mice were injected three times over an 8-hour period with a total of 48 muci 3H-T/gm of body weight and were sacrificed 1, 3, 5, 9 and 17 days afterwards. Radioautographs of the ovaries showed significantly higher grain counts in oocytes of follicles that are in the antrum formation stage. The radioautographic visualization of DNase digestible 3H-thymidine incorporation into the juxtanucleolar region in oocytes of mature mice occurs in association with ooctye growth in follicles that are in the antrum formation stage. The scheduled disappearance of this juxtanucleolar oocyte DNA and its label during later oocyte growth suggests a degradation or dispersion of this labeled DNA prior to ovulation.
Basal cell carcinoma with sebaceous gland differentiation has been described in mice and humans but spontaneous skin tumors of this type are uncommon in the rat.The tumor specimen was taken from a 26 month old male Wistar rat. Electron microscopy specimens were fixed by immersion in cacodylatebuffered 4% glutaraldehyde, post-fixed in 1% osmium tetroxide, dehydrated, cleared and embedded by standard procedures. Semi-thin (μm) sections were stained with ethanolic uranyl acetate followed by lead citrate, then examined on a Philips EM201 electron microscope.
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