MILLER and SUMIDA: DEVELOPMENT OF CARANX MATE 



The perivitelline space was not evident in the 

 early blastoderm stages but developed as the 

 egg advanced. 



Yolk: 

 (diameter) 660± 23 m. 



The segmentation of the yolk was apparent 

 in the form of irregular polygons across the 

 egg diameter in the early stage eggs (not 

 illustrated). This pattern was lost with 

 preservation of the eggs in 2.5% formalde- 

 hyde, whereupon the yolk took on a "bubbly" 

 irregular appearance. 



Embryo development: 



The optic vesicles were evident on the young 

 embryo before blastopore closure of the egg 

 (not illustrated). Initiation of somite develop- 

 ment in the anterior end of the embryo was 

 also observed before closure of the blasto- 

 pore. Kupffer's vesicle was conspicuous at 

 the tip of the rudimentary tail bud. 



Pigmentation: 



No pigmentation was present in the egg or 

 embryo during this stage. 



Duration of early stage: 



11-12 h subsequent to capture. Estimated 

 total time — 14 h. 



Middle stage 



Following blastopore closure to separation of the 



tail bud from the yolk (Figure IB). 



Noteworthy events: 



Advanced development of the embryo and 

 pigmentation patterns. Egg size, width of 

 perivitelline space, etc., same as above. 



Oil globule: 



The oil globule remained nearly centered 

 between the developing head and tail of the 

 embryo. The underside of the oil globule 

 (closest to the embryo) appeared heavily 

 pigmented during the latter part of the 

 middle stage owing to melanophores which 

 had migrated from the surrounding yolk 

 surface (Figure IC). 



Yolk pigmentation: 



In the early middle stage, numerous small 

 melanophores were observed overlying the 

 anterior surface of the yolk surrounding the 

 oil globule (Figure IB). Most of these melano- 

 phores migrated during the middle stage and 

 aggregated on the underside of the oil 

 globule. 



Embryo pigmentation: 



Small, faintly pigmented melanophores first 

 appeared along the lines separating the 

 developing somites and spread laterally 

 covering the dorso-lateral region of the body. 

 A conspicuous patch of pigment was notice- 

 able at the anterior and posterior margins 

 of the optic vesicles, and a small cluster of 

 melanophores in the area of the snout. Later 

 in this stage, larger melanophores appeared 

 in an irregular line along the medial dorsal 

 surface of the body (Figure ID). 



Somite development: 



By the end of the middle stage, 21 well- 

 defined myomeres could be counted. Kupffer's 

 vesicle was still evident in the middle stage. 



Duration of the middle stage: 

 11-12 h at24.5°C. 



Late stage 



Tail bud completion to hatching of larva (Figure 



IE). 



Oil globule: 



When the advanced embryo had coiled around 

 the yolk, the oil globule shifted in position 

 and became situated closer to the head rather 

 than maintaining a median position under 

 the embryo. Pigmentation became more 

 abundant, extending over the hemisphere of 

 the underside in contrast to the small, dense 

 cluster in the middle stage. Virtually no 

 pigment remained on the surrounding yolk. 



Embryo pigmentation: 



Dense pigmentation remained on the dorso- 

 lateral surfaces of the body. Melanophores 

 appeared over the top of the head in addition 

 to those on the snout and along the anterior 

 and posterior margins of the eye. A band of 

 small melanophores developed around the 

 body near the tail region. There also appeared 

 a ring of melanophores on the yolk surface 

 posterior to the tip of the tail bud. This was 

 subsequently lost in the final span of the late 

 stage when fin fold formation was com- 

 pleted and tail flexure occurred. Kupffer's 

 vesicle was observed in the early part of the 

 late stage but was subsequently lost. 



Somite development: 



The adult complement of 24 somites was 

 attained in the late stage embryo. 



Duration of late stage: 

 0.5-1 h at 24.5°C. 



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