Search Results

You are looking at 1 - 6 of 6 items for

  • Author: D. DANON x
Clear All Modify Search
Free access

U. LAVON, R. VOLCANI and D. DANON

Summary.

Changes occurring in the proteins of bovine spermatozoa during their migration from the caput to the cauda epididymidis were studied.

The percentage of total nitrogen in the dry matter was greater in the cauda than in the caput spermatozoa, but the nitrogen content/109 cells was less in the cauda spermatozoa. The amount of DNA for the same number of cells remained constant during this stage of maturation. The decrease in the nitrogen content indicated a loss of protein during maturation of bovine spermatozoa in the epididymis. Amino acid analysis of the dry matter of the sperm cells showed an increase in the percentage of arginine and cystine and a decrease in the percentage of glutamic and aspartic acids, alanine, methionine, isoleucine and leucine during passage of spermatozoa through the epididymis. Lipoprotein content decreased during the maturation of the sperm cells, and a slight increase occurred in several of the other proteins. Amino acid analysis of the extracted proteins showed differences in the percentage of several amino acids between caput and cauda spermatozoa in the F1 and F2 fractions. Gel disc electrophoresis of the various caput and cauda sperm proteins indicated a different number of bands and a different colour intensity for those fractions in which a different amino acid composition was found.

The results suggest that the lipoproteins of the cell membrane may be the site of alterations in the quantity, composition and electrophoretic behaviour of the proteins of bovine spermatozoa during their maturation.

Free access

U. LAVON, R. VOLCANI and D. DANON

Previous estimates of dry matter content in spermatozoa have been variable (Ray Sarkar, Luecke & Duncan, 1947; VanDemark, 1948; Barer, Ross & Tkaczyk, 1953) but some of the methods employed might have altered the chemical composition of the spermatozoa. Therefore, a method was needed that would facilitate the separation of spermatozoa from seminal plasma and, at the same time, would ensure minimal exchange of water and other substances to and from the cells.

Ballentine & Burford (1960) have separated, simply and effectively, various cells from their suspending medium by differential flotation (df). Our previous studies on the specific gravity (sp.gr.) and density distribution of bull spermatozoa were based on df. The spermatozoa thus separated from the seminal plasma are not altered in their composition

Free access

U. LAVON, R. VOLCANI and D. DANON

Summary.

Several changes occurring during sperm maturation in the epididymis were determined either for spermatozoa obtained from consecutive ejaculates or from the caput and the cauda epididymidis.

A significant decline was found in the fresh weight of the cells during maturation and was attributed to dehydration and to a loss of certain components from the cells. This was proved by the increase in the % dry matter and by the decrease in the content of the dry matter, the total lipids and of the main lipid fractions of the cells during maturation.

The increase in the % dry matter and the decrease in the % total lipids in the dry matter explain the increase in the specific gravity of spermatozoa during maturation.

Free access

U. LAVON, R. VOLCANI, D. AMIR and D. DANON

There are a few reports on the changes in specific gravity (s.g.) during maturation and ageing of spermatozoa. Lindahl & Kihlström (1952) found the s.g. of bull spermatozoa to range between 1·240 and 1·334. The s.g. decreased from 1·2867 to 1·2668 when three consecutive ejaculates were collected. Lindahl & Thunqvist (1965) found a value of 1·10 to 1·12 for the s.g. of bull epididymal spermatozoa and a value of 1·21 to 1·33 for ejaculated spermatozoa. Assuming that spermatozoa from the epididymis and from later ejaculates are younger than those from the first ejaculates, they suggested that the s.g. of spermatozoa increases with maturation and ageing.

Spermatozoa were taken from different parts of the bull testis in order to ascertain whether their s.g.

Free access

U. LAVON, R. VOLCANI, D. AMIR and D. DANON

There are few reports in the literature concerning the specific gravity (s.g.) of mammalian spermatozoa and seminal plasma. Lindahl & Kihlstrom (1952) using umbradil salts of methylglucamine as the suspending medium found bull spermatozoa to have a specific gravity of 1·241 to 1·335. Lindahl & Thunqvist (1965) using Ficoll (polysaccharide of sucrose) obtained values of 1·21 to 1·33. These results are considerably higher than the specific gravity of 1·0975 reported by Yamane (1920) for the stallion, and 1·132 reported by Beatty (1964) for the rabbit. They also seem very high in view of the chemical composition of the dry matter and water content as given by Mann (1964) and VanDemark (1948).

The specific gravity of bull seminal plasma reported by Anderson (1946) was 1

Free access

BRITTA HARDY, D. DANON, A. ESHKOL and B. LUNENFELD

Summary.

The ultrastructure of ovaries of infant mice deprived of gonadotrophins was compared to the normal developmental pattern and to that of animals deprived of endogenous gonadotrophins but receiving FSH.

In the absence of circulating gonadotrophins, structural changes were observed ; granulosa-cell nuclei were irregularly shaped rather than round, and the spaces between the granulosa cells disappeared as did the spaces between the granulosa cells and the oocyte.

The most striking effect was observed in the zona pellucida, the width of which diminished and became irregular. The number of cell processes within the zona pellucida was markedly reduced.

These changes are tentatively attributed to alteration in the structure of the granulosa cell. Substitution with FSH partly prevented these changes, indicating that FSH has a rôle to play in the preservation of the integrity of the granulosa-cell membrane.