Histological and cytological studies of the corpus luteum and resorptive bodies of Dysdercus similis Freeman

Bhide, M.

Folia Morphologica 34(3): 291-300

1986


ISSN/ISBN: 0015-5640
PMID: 3781402
Document Number: 271468
After ovulation, the ovaries of Dysdercus similis are seen to contain a number of rounded greenish bodies at the junction of one or more ovarioles and the peduncle. These coloured bodies, which are generally formed after ovulation, are known as "corpora lutea", but if they are formed as a result of oocyte resorption they are termed "resorptive bodies". The follicular epithelium plays an important role in the formation and resorption of the corpus luteum. First of all, the cellular character of the follicular epithelium is completely obliterated and a syncytium containing irregularly scattered pyknotic nuclei is formed. Pyknosis leads to resorption and reduction of the size of the corpus luteum. The tunica propria progressively shrinks, as a sign of active resorption. Resorption of the corpus luteum is completed when the next follicle matures and is ready for ovulation. The tunica propria is extremely rich in protein-a characteristic which increases from just after laying up to the last stage. Conversely, the number of pyknotic nuclei, mitochondria and Golgi bodies steadily decreases. The pyknotic nuclei are osmiophilic; as a result of their destruction, a number of scattered osmiophilic granules are found in the cytoplasmic syncytium. Under given adverse physiological or oecological conditions, the terminal oocytes of Dysdercus similis do not all ovulate, but remain behind and are resorbed, so that they form coloured "resorptive bodies". Here the follicular epithelium participates actively in resorption. In the case of normal oocytes it consists of a single cell layer, but at the proximal and distal end of resorbed oocytes it is composed of two or more layers. It also sends into the ooplasm projections which are soon detached from the follicular epithelium proper and appear in the ooplasm as cell islands. These cells islands-like the follicular epithelial cells themselves-become lecitholytic and act as vitellophages; they help in the destruction and resorption of glycoproteins and lipoproteins by secreting a proteolytic enyzme which breaks down these complex protein molecules into their monomers amino acids), making them more suitable for resorption by the haemolymph. The follicular epithelium of the resorbed oocyte is rich in protein, with some osmiophilic granules inside the cells. Numerous PYP and lipid bodies are to be found in the ooplasm. The L3 lipid bodies are broken down to L2 bodies, which in turn are broken down to L1 bodies and a large number of osmiophilic granules; these are then resorbed by the follicular epithelial cells and the lecitholytic cells released into the ooplasm. Large numbers of mitochondria and Golgi bodies are to be found near the follicular epithelium. Corpus luteum formation and oocyte degeneration are in many ways similar. In both, tissue is continuously resorbed and pigment is deposited. No new tissue is formed at any stage in either process.

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