Millepora platyphylla: interface between medusa and ampulla.
Phase contrast
I was exploring phase contrast with a new--to me--used Zeiss Plan Ph2 40/0.65 160/0.17 objective. This slide was stained using Cason Trichrome stain.
This shows a part of a medusa, with scarcely developed ova. I think most of will contribute themselves to the growth of the three, or possibly, sometimes, four ova that eventually develop. These may be called nurse cells?
A meshwork of vacuolated material---lipid droplets---is being traversed by some zooxanthellae. The eggs of Millepora spp. are hosts to symbiotic dinoflagellates (zooxanthellae) before their release and fertilization. This is part of the process.
The ampulla is a hollow vessel that holds the medusa as it develops. The tissue outside the medusa is apparently related to the ampulla. Intense yellow indicates calicoblastic tissue. I am interested that in this image the yellow resolves into green and yellow particles; I wonder, does this point to two separate structures involved in producing---and in this species sometimes dissolving?---Calcium Carbonate. To my knowledge the structural changes involved in generation of ampullae, in conjunction with growth of the medusae and development of the gametes in both male and female medusae has not been worked out in its entirety. The reproductive events, per se, have been studied closely.
