Why male managers find it easier getting to the top
From an FT article, Getting women on board by Alison Maitland:

Male managers receive more specialist training for promotion than female managers from the start of their careers and benefit from more support in new roles, an international study by DDI, a talent management consultancy, reveals today.

Starting at junior management level, 28 per cent more men than women receive specialist development via high-potential groups or “talent pools”, according to data from 10,000 business leaders in 376 organisations. At executive level, 50 per cent more men than women get such help. Women, who also receive less support in career transitions such as promotions, may not be aware of discrimination, as selection processes and mentor schemes are “shrouded in secrecy”, says the report, Holding Women Back.

This suggests that the "slippery pole" is a better explanation of low representation of women at executive levels than the "glass ceiling". The same thing goes on in academia; I'd be interested to see independent investigation into this latter phenomenon.