Detection of blob in a sperm cell

I was trying to detect how many vacuoles are there in a sperm cell. Following the picture.

I have thought of a few ways, first is perform the laplace of gaussian to the image, it will give me the gradient of the map, and I may get the boundary. But there is one problem, the boundary is not closed, so it will be hard to tell how many blobs are there.

I wonder if anyone have any different ideas.

[KSSV]

Attach one single image.