No abstract

Histochemical analysis of the developing chick axial region indicated very little sulphated glycosaminoglycan present in early embryonic stages (stage 17) and this appeared to be confined extra-cellularly to the region of the notochordal sheath. Strongly acidic material was observed in the cytoplasm of cells in all examined axial areas, viz., dermatome, myotome, sclerotome, neural tube and notochord. Weakly acidic anionic glycosaminoglycans were present i n the extracellular portion of all axial areas and increased in concentration during development, particularly i n the neural tube and the sclerotome. At the same time the concentration of sulphated anionic glycosaminoglycans also increased in the extracellular matrix of all axial areas. By stage 25 the extracellular matrix of the perichordal scleratome appeared to

These studies were designed to provide information on ultrastructural changes in the differentiating plerocercoid cuticle of Schistocephalus solidus. Portions of the cuticle retain an apparently primitive or undifferentiated morphology during growth with the most profound changes being restricted to the thick superficial cuticle of each segment. Although the velum remains thin and similar in many ways to the entire cuticle of small worms, the superficial cuticle increases greatly in depth, changes in structural composition, develops a basal mitochondria population, and elaborates an extensive surface layer of cuticular protrusions. These morphological observations are correlated with previous histochemical results.

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The effects of estradiol and progesterone treatment on the growth and differentiation of the quail oviduct have been investigated in terms of morphology, growth, and biochemical differentiation. Histologically, estradiol induced the formation of tubular gland cells by 5 days of treatment, and epithelial differentiation by 10 days of treatment. Progesterone treatment appeared to enhance epithelial differentiation slightly, compared with continued estrogen treatment. The estradiol treatment also enhanced the growth of the oviduct, as indicated by increases in size, weight, and the content of the tissue constituents protein, RNA, and DNA. Estradiol treatment also induced the synthesis of two specific proteins, ovalbumin and lysozyme; however, only progesterone induced the synthesis of the protein avidin. Withdrawal from both types of treatment for 10 days caused a loss of cells and of tissue constituents. This loss was greater in those birds withdrawn from sequential estrogen-plus-progesterone treatment than in those withdrawn from estrogen treatment. In some cases, specific proteins were also absent in oviducts from birds withdrawn from treatment.