Light and scanning electron microscopic studies on the effect of biocidal plant sap on the gills of a hill stream fish, Garra lamta (Ham.)

The effect of a biocidal plant sap ( Terminalia tomentosa ) on the gills of a swift-current-adapted hill-stream fish, Garra lamia , has been investigated using light and scanning electron microscopy. The biocidal plant sap affected the dissociation of the gill filament and lamellar epithelia to expose their microvasculature. Some findings on the microvasculature are discussed in the light of their probable functions. Fusion of lamellae and prominent chloride cells are further effects of the plant sap, and their impact on respiratory and osmoregulatory functions of the fish are discussed.
Use of biocidal plant sap in mass killing of hill-stream fish is considered in relation to conservation.     

Structure of the integument of a fresh-water teleost,Bagarius bagarius (Ham.) (Sisoridae,pisces)

The skin of Bagarius bagarius (Ham.) is devoid of scales but is rough due to the presence of numerous pentagonal epidermal elevations, which are separated by deep furrows at regular intervals. These elevated pentagonal regions of the epidermis are covered by dead cornified cells in the form of caps. As the old cap goes off a new one is formed by the death of the underlying epidermal cells. The middle layer of the epidermis is mainly composed of well defined polygonal cells. Their cytoplasm is granular in nature and give reactions for protein bound sulphydryl groups. The stratum germinativum is composed of two types of basal cells, the columnar cells and the spherical cells. The flask shaped mucous glands are restricted to the epidermal furrows and secrete either neutral or acidic mucopolysaccharides. Certain large specialysed granular cells are found in the epidermis which are grouped around the taste buds. These specialysed cells may be the photocytes. Two layers of the dermis can be distinguished—the relatively thin stratum laxum and the thick stratum compactum. Dermal papillae mainly support the taste buds. The pigment cells are arranged in two layers in the dermis. The subcutis is composed of loose connective tissues, richly infiltrated with the fat cells, nerves and blood capillaries.     

Studies on blood components of an air-breathing siluroid fish, Heteropneustes fossilis (Bloch) in relation to body weight.

Different haematological parameters have been studied in relation to the body weight of Heteropneustes fossil (Bloch). The erythrocytes and leucocytes number and haemoglobin concentration increases from lower to higher weight groups. The heart weight also increases along with other blood components. With the unit increase in the body weight of this fish, the heart weight, erythrocytes, leucocytes and haemoglobin increase by a fractional power of 0.85700, 0.13480, 0.13215 and 0.22876, respectively. This shows that haemoglobin increases at a higher rate than erythrocyte number. The coefficient of correlation between body weight and erythrocyte (r = 0.70015), leucocytes (r = 0.95861), haemoglobin (r = 0.96615) and heart weight (0.97577) indicate high degree of correlation. The erythrocytes and leucocytes count and haemoglobin concentration per gram body weight is higher in younger fishes and decrease as the animal grows in size. The haematocrit values and mean corpucsular volumes decrease from lower to higher weight groups, whereas mean corpuscular haemoglobin concentration increases with body weight. The erythrocyte cell surface has a decreasing trend from lower to higher weight group. Due to difference in the rate of decrease of greatest and least diameter of erythrocytes, the elliptical shape of R.B.C. which is common in younger animals, becomes circular in higher weight group. The non-granulocytes increase constantly while the percentage of granulocytes decreases from lower to higher weight groups. The lymphocytes constitute the main bulk of all the leucocytes. The total lymphocytes also increase with the body weight. Spindle cells and monocytes are relatively less in numbers. The percentage of eosinophils, basophils and neutrophils also decrease from lower to higher weight groups.     

On the structure of retina of a fresh-water mullet, Rhinomugil corsula (Mugilidae, Pisces).

1. The structure of the eye-ball of Rhimomugil corsula has been described. 2. A mid-horizontal ridge (band) along the vitreal surface of the retina in each eye of R. corsula has been observed which divides the retina into a superior and an inferior hemispheres probably adapted for aquatic (dim-light vision) and aerial (bright-light vision) vision. 3. The superior hemisphere has been provided with poorly developed choroid gland and scarce pigment in the pigment epithelial cells. 4. The visual cell layer in the retina of the superior hemisphere contains both single and twin cones. They are alternately arranged in parallel rows. 5. The external and internal limiting membranes have been observed in both the hemispheres under light microscope. 6. The outer plexiform layer of the superior hemisphere contains many horizontal cells arranged into four distinct rows. 7. The inferior hemisphere has a well developed choroid gland, and dense pigment in the pigment epithelial cells.     

Changes in uterine phosphatase levels in mice deprived of LH during early pregnancy.

Mice injected with normal rabbit serum on Day 4 of gestation showed a progressive increase in specific alkaline and acid phosphatase activities on Days 6 and 7. Mice injected with antiserum to LH on Day 4 showed a significant decrease in specific alkaline phosphatase activity estimated biochemically on Days 6, 7 and 8, but this decrease was histochemically evident only on Day 8. Similarly, acid phosphatase activity in antiserum-treated mice was significantly increased on Days 6, 7 and 8 when estimated biochemically, but only on Day 8 when studied histochemically.     

Effect of environmental factors on the activity of thyroid gland in an air breathing siluroid fish Heteropneustes fossilis Bloch.

1. Studies on cyclic activity of thyroid in relation to environmental factors were made in an air breathing siluroid fish, H. fossilis. 2. The activity of thyroid gland showed parallelism with water temperature and photoperiod but from the regression analysis it was evident that the effect of photoperiod on thyroid activity is more pronounced than the effect of water temperature. 3. The maximum thyroid activity coincides well with the breeding phase of this animal.