Естественнонаучные проблемы Арктического региона : 10-я региональная научная студенческая конференция, Мурманск, 14 мая 2010г. : тезисы конференции. Ч. 2. Секции "Биология и медицина", "Гуманитарные проблемы". Мурманск, 2010.

broodstock held in captivity at the Marine Research Center. With refer­ ence to the main external morphological characteristics and source of food, larva development was divided into four stages: (1) Yolk sac larva (0-9 DPH), (2) Preflexion larva, (10-25 DPH); (3) Flexion larva (26-33 DPH); (4) Postflexion larva (34-49). The organ development in larvae was very prominent during the first three stages. Development during stage 4 was characterized by the proliferation and growth of existing structures. As in most marine fish species at hatching, the mouth and anus were closed, eyes were not pigmented, and digestive tract was an undif­ ferentiated and straight tubular segment. The majority of the organs were observed as undifferentiated groups of cells or primordial structures. Pericardic cavity, urinary bladder and exocrine pancreas anlages were seen. By the end of lecitotrophic period of stage 1 both the mouth and the anus opened in conjunction with the differentiation of the digestive tract. Buccopharyngeal cavity, oesophagus, stomach, midgut and hindgut were distinguished. Primordial structures of liver, swim bladder, gall bladder, gills and kidney appeared. At stage 1 lecitoexotrophic period started when eyes were pigmented and larvae were ready for capture of the prey and feeding. As ingestion of prey began, the digestive processes continued developing with the appearance of mucous cells in the oesophagus, gut folds and brush border in the intestine. The circulatory system became functional, with the compartmentalization of the heart. During stage 2 (and 3) excretory system became functional with the development of glomeruli corpuscles, tubules and collecting ducts, and first haematopoi­ etic tissue appeared. Gall bladder was formed and observed at these stages. At the end of the stage endocrine part of pancreas - Langerhans islets were evident. Taste buds were seen in the oesophagus and skin. Throughout stage 3 thyroid follicles appeared, gill structures continued developing, pituitary appeared. Number of mucous cells in the oesopha­ gus increased and first mucous cells appeared in the gill opening. During stage 4, gill filaments and lamellae proliferated, the number of mucous cells in gill opening region increased. Most organs essentially exhibited an increase in tissue structure and size. 36