Induction of the endogenous gonadotrophin surge for oocyte maturation with intra-nasal gonadotrophin-releasing hormone analogue (buserelin): effective minimal dose

From 1985-1987, a total of 34 couples undergoing superovulation for a single in-vitro fertilization (IVF) cycle with clomiphene citrate and purified follicle stimulating hormone (FSH) or human menopausal gonadotrophin (HMG) were randomly allocated doses of intra-nasal buserelin to induce an endogenous gonadotrophin surge, prior to oocyte collection. The doses ranged from a single 25 microg dose to 100 microg every 4 h for 20 h. In three cycles the treatment was abandoned because of a poor ovarian response. In the remaining 31 cycles buserelin was given to induce the endogenous gonadotrophin surge, but there was evidence of premature luteinization in eight cycles and a premature gonadotrophin surge in four cycles. Although a single dose as low as 40 microg induced a surge and resulted in a pregnancy, a single dose of 50 microg proved the most effective minimal dose consistently to induce a gonadotrophin surge and oocyte maturation. Recent reports using gonadotrophin-releasing hormone (GnRH) analogues to induce a gonadotrophin surge has prompted publication of this previously unpublished data.      

The morphology of the pecten oculi of the ostrich, Struthio camelus

The pecten oculi is a structure peculiar to the avian eye. Three morphological types of pecten oculi are recognized: conical type, vaned type and pleated type. The pleated type has been well studied. However, there exists only scanty data on the morphology of the latter two types of pectens. The structure of the vaned type of pecten of the ostrich, Struthio camelus was investigated with light and electron microscope. The pecten of this species consists of a vertical primary lamella that arises from the optic disc and supports 16–19 laterally located secondary lamellae, which run from the base and confluence at the apex. Some of the secondary lamellae give rise to 2 or 3 tertiary lamellae. The lamellae provide a wide surface, which supports 2–3 layers of blood capillaries. Pigmentation is highest at the distal ends of the secondary and tertiary lamella where blood capillaries are concentrated and very scanty on the primary and the proximal ends of the secondary lamella where the presence of capillaries is much reduced. In contrast to the capillaries of the pleated pecten, the endothelium of the capillaries in the pecten of the ostrich exhibits very few microvilli. These observations suggest that the morphology of the pecten of the ostrich, a flightless ratite bird is unique to the pleated pecten and is designed to meet the balance between optimal vision and large surface area for blood supply and yet ensuring it is kept firmly erect within the vitreous.     

Hyperlipidemia, hypercoagulability, and accelerated thrombosis: studies in congenitally hyperlipidemic rats and in rats and monkeys with induced hyperlipidemia

Inbred Carworth Farms Nelson (CFN) congenitally hyperlipidemic rats had significantly shorter coagulation and prothrombin times and higher levels of coagulation factors, II, V, VII, VIII, and X than did controls. Conversely, congenitally hypolipidemic rats of the same strain had significantly longer coagulation and prothrombin times and lower levels of factors II, V, VII, X and XII and of blood platelets than did controls. A loop-shaped polyethylene cannula was inserted into the aorta to assess the potential for thrombosis. The hyperlipidemic group obstructed this significantly faster and the hypolipidemic group slower than did the controls. Normal CFN rats made hypertensive by unilateral renal artery clip developed hypertension together with significantly elevated serum cholesterol and factor VII and X levels. Rhesus monkeys with diet-induced hyperlipidemia showed shorter prothrombin times and higher factor X levels than did controls on normal diet. By selective breeding, two groups of squirrel monkeys were obtained. Both groups had similar serum cholesterol levels on a normal diet but one group (hyperresponders) showed higher serum cholesterol levels on a cholesterol-containing diet than did the other (hyporesponder) group. Both groups showed significantly elevated levels of factors II, V, VII, IX and X on a cholesterol-containing diet. There was good correlation between the levels of many coagulation factors and serum cholesterol in both rats and monkeys. If thrombosis is important in the genesis of atherosclerosis, these findings could indicate that elevation of plasma lipids may play a role, via the coagulation pathway, in the production of human vascular disease.